Add -Wno-unit_address_vs_reg to avoid dtc warning

For a long time there has been this annoying set of warnings
when building Adafruit_BBIO:

overlays/ADAFRUIT-SPI0-00A0.dtbo: Warning (unit_address_vs_reg): Node /fragment@0 has a unit name, but no reg property
overlays/ADAFRUIT-SPI0-00A0.dtbo: Warning (unit_address_vs_reg): Node /fragment@1 has a unit name, but no reg property
overlays/ADAFRUIT-SPI1-00A0.dtbo: Warning (unit_address_vs_reg): Node /fragment@0 has a unit name, but no reg property
overlays/ADAFRUIT-SPI1-00A0.dtbo: Warning (unit_address_vs_reg): Node /fragment@1 has a unit name, but no reg property
overlays/ADAFRUIT-UART1-00A0.dtbo: Warning (unit_address_vs_reg): Node /fragment@0 has a unit name, but no reg property
overlays/ADAFRUIT-UART1-00A0.dtbo: Warning (unit_address_vs_reg): Node /fragment@1 has a unit name, but no reg property
overlays/ADAFRUIT-UART2-00A0.dtbo: Warning (unit_address_vs_reg): Node /fragment@0 has a unit name, but no reg property
overlays/ADAFRUIT-UART2-00A0.dtbo: Warning (unit_address_vs_reg): Node /fragment@1 has a unit name, but no reg property
overlays/ADAFRUIT-UART4-00A0.dtbo: Warning (unit_address_vs_reg): Node /fragment@0 has a unit name, but no reg property
overlays/ADAFRUIT-UART4-00A0.dtbo: Warning (unit_address_vs_reg): Node /fragment@1 has a unit name, but no reg property
overlays/ADAFRUIT-UART5-00A0.dtbo: Warning (unit_address_vs_reg): Node /fragment@0 has a unit name, but no reg property
overlays/ADAFRUIT-UART5-00A0.dtbo: Warning (unit_address_vs_reg): Node /fragment@1 has a unit name, but no reg property

I noticed that installing bb.org-overlays does not generate
these warnings despite having similar device tree syntax:
https://github.com/beagleboard/bb.org-overlays/blob/master/Makefile#L35

I decided to go with Robert Nelson's judgement and add the flag
to avoid the dtc warning when building Adafruit_BBIO.

Author: pdp7

overlays/builder.py

@@ -5,13 +5,13 @@
 
 def compile():
     #SPI Overlays
-    call(["dtc", "-O", "dtb", "-o", "overlays/ADAFRUIT-SPI0-00A0.dtbo", "-b", "o", "-@", "overlays/ADAFRUIT-SPI0-00A0.dts"])
-    call(["dtc", "-O", "dtb", "-o", "overlays/ADAFRUIT-SPI1-00A0.dtbo", "-b", "o", "-@", "overlays/ADAFRUIT-SPI1-00A0.dts"])
+    call(["dtc", "-Wno-unit_address_vs_reg", "-O", "dtb", "-o", "overlays/ADAFRUIT-SPI0-00A0.dtbo", "-b", "o", "-@", "overlays/ADAFRUIT-SPI0-00A0.dts"])
+    call(["dtc", "-Wno-unit_address_vs_reg", "-O", "dtb", "-o", "overlays/ADAFRUIT-SPI1-00A0.dtbo", "-b", "o", "-@", "overlays/ADAFRUIT-SPI1-00A0.dts"])
     #UART Overlayss
-    call(["dtc", "-O", "dtb", "-o", "overlays/ADAFRUIT-UART1-00A0.dtbo", "-b", "o", "-@", "overlays/ADAFRUIT-UART1-00A0.dts"])
-    call(["dtc", "-O", "dtb", "-o", "overlays/ADAFRUIT-UART2-00A0.dtbo", "-b", "o", "-@", "overlays/ADAFRUIT-UART2-00A0.dts"])
-    call(["dtc", "-O", "dtb", "-o", "overlays/ADAFRUIT-UART4-00A0.dtbo", "-b", "o", "-@", "overlays/ADAFRUIT-UART4-00A0.dts"])
-    call(["dtc", "-O", "dtb", "-o", "overlays/ADAFRUIT-UART5-00A0.dtbo", "-b", "o", "-@", "overlays/ADAFRUIT-UART5-00A0.dts"])
+    call(["dtc", "-Wno-unit_address_vs_reg", "-O", "dtb", "-o", "overlays/ADAFRUIT-UART1-00A0.dtbo", "-b", "o", "-@", "overlays/ADAFRUIT-UART1-00A0.dts"])
+    call(["dtc", "-Wno-unit_address_vs_reg", "-O", "dtb", "-o", "overlays/ADAFRUIT-UART2-00A0.dtbo", "-b", "o", "-@", "overlays/ADAFRUIT-UART2-00A0.dts"])
+    call(["dtc", "-Wno-unit_address_vs_reg", "-O", "dtb", "-o", "overlays/ADAFRUIT-UART4-00A0.dtbo", "-b", "o", "-@", "overlays/ADAFRUIT-UART4-00A0.dts"])
+    call(["dtc", "-Wno-unit_address_vs_reg", "-O", "dtb", "-o", "overlays/ADAFRUIT-UART5-00A0.dtbo", "-b", "o", "-@", "overlays/ADAFRUIT-UART5-00A0.dts"])
 def copy():
     for fl in glob.glob("/lib/firmware/ADAFRUIT-SPI*-00A0.dtbo"):
         os.remove(fl)
@@ -24,4 +24,4 @@ def copy():
     shutil.move("overlays/ADAFRUIT-UART1-00A0.dtbo", "/lib/firmware/ADAFRUIT-UART1-00A0.dtbo")
     shutil.move("overlays/ADAFRUIT-UART2-00A0.dtbo", "/lib/firmware/ADAFRUIT-UART2-00A0.dtbo")
     shutil.move("overlays/ADAFRUIT-UART4-00A0.dtbo", "/lib/firmware/ADAFRUIT-UART4-00A0.dtbo")
-    shutil.move("overlays/ADAFRUIT-UART5-00A0.dtbo", "/lib/firmware/ADAFRUIT-UART5-00A0.dtbo")
+    shutil.move("overlays/ADAFRUIT-UART5-00A0.dtbo", "/lib/firmware/ADAFRUIT-UART5-00A0.dtbo")