RGBW handles None g/b values

Found during testing

Signed-off-by: David Greaves <david@dgreaves.com>

Author: lbt

library/rpi_ws281x/rpi_ws281x.py

@@ -11,6 +11,10 @@ def __new__(self, r, g=None, b=None, w=None):
         else:
             if w is None:
                 w = 0
+            if g is None:
+                g = 0
+            if b is None:
+                b = 0
             return int.__new__(self, (w << 24) | (r << 16) | (g << 8) | b)
 
     @property