nrf: make neopixel support optional

Add a conditional around the call to neopixel_write(), allowing us
to build for nrf without neopixel support.

Signed-off-by: Sean Cross <sean@xobs.io>

ports/nrf/supervisor/port.c

@@ -104,7 +104,10 @@ void reset_port(void) {
     i2c_reset();
     spi_reset();
     uart_reset();
+
+#if CIRCUITPY_NEOPIXEL_WRITE
     neopixel_write_reset();
+#endif
 
 #if CIRCUITPY_AUDIOBUSIO
     i2s_reset();