Fix Mongoose and Frozen include paths

In preparation for making moving to lib.
Reduce amount of makefile copypasta a bit.

CL: none

PUBLISHED_FROM=70a016491f9605e37708385bdd698f48a8d64119

Author: Deomid Ryabkov

src/mgos_arduino.cpp

@@ -10,7 +10,7 @@
 #include <Arduino.h>
 
 #include "common/cs_dbg.h"
-#include "mongoose/mongoose.h"
+#include "mongoose.h"
 
 #include "mgos_gpio.h"
 #include "mgos_hal.h"