rp2/boards: Add neopixel.py to manifest.py.

Because machine.bitstream is now implemented on the rp2 port.

Author: robert-hh

ports/rp2/boards/manifest.py

@@ -1,3 +1,4 @@
 freeze("$(PORT_DIR)/modules")
 freeze("$(MPY_DIR)/drivers/onewire")
 include("$(MPY_DIR)/extmod/uasyncio/manifest.py")
+include("$(MPY_DIR)/drivers/neopixel/manifest.py")