Remove 400khz flag from neopixel_write to work with CircuitPython 0.9.0 API change.

CircuitPython 0.9.0 removed this bool for SAMD21 port to save space.  Updating library to conform.  NOTE this _requires_ using the latest 0.9.0 release to make NeoPixels work!

Author: tdicola

neopixel.py

@@ -34,4 +34,4 @@ def fill(self, color):
             self[i] = color
 
     def write(self):
-        neopixel_write(self.pin, self.buf, True)
+        neopixel_write(self.pin, self.buf)