ARM - ws2812 bitbang (#7173)

* Initial ARM bitbang ws2812 driver

* Unify chibios platform to run rgblight_task

* Remove 'avr only' comments from ws2812 docs

* Remove 'avr only' comments from ws2812 docs

* Unify chibios platform to run rgblight_task - review comments

* Remove debug flags from keymap

* Add comments from review

* Add defines for STM32L0XX

* Attempt to get arm ws2812 working on multiple gcc versions

docs/feature_rgb_matrix.md

@@ -107,7 +107,7 @@ Where `X_Y` is the location of the LED in the matrix defined by [the datasheet](
 
 ---
 
-### WS2812 (AVR only)
+### WS2812
 
 There is basic support for addressable RGB matrix lighting with a WS2811/WS2812{a,b,c} addressable LED strand. To enable it, add this to your `rules.mk`: