Unify RGB and RGBW commands (#7297)

* Fix unicode in comments

Co-Authored-By: fauxpark <fauxpark@gmail.com>

* Remove separate RGBW implementation for a unified function

* Set White to 0 in RGBW LEDs

This is just to get this working, later, proper brightness can be handled elsewhere.

* Use us instead of nanoseconds(?) since it renders correctly on web

* Remove RGBW function from arm/ws2812.h

* Remove RGBW function from arm/ws2812.c

* Formatting changes

* Add doc info

drivers/avr/ws2812_i2c.c

@@ -1,6 +1,10 @@
 #include "ws2812.h"
 #include "i2c_master.h"
 
+#ifdef RGBW
+#    error "RGBW not supported"
+#endif
+
 #ifndef WS2812_ADDRESS
 #    define WS2812_ADDRESS 0xb0
 #endif
@@ -21,11 +25,3 @@ void ws2812_setleds(LED_TYPE *ledarray, uint16_t leds) {
 
     i2c_transmit(WS2812_ADDRESS, (uint8_t *)ledarray, sizeof(LED_TYPE) * leds, WS2812_TIMEOUT);
 }
-
-// Setleds for SK6812RGBW
-void ws2812_setleds_rgbw(LED_TYPE *ledarray, uint16_t leds) {
-// not supported - for now error out if its enabled
-#ifdef RGBW
-#    error "RGBW not supported"
-#endif
-}