Use opendrain pin with external pullup again (#14474)

platforms/chibios/drivers/ws2812_pwm.c

@@ -46,7 +46,7 @@
 #    endif
 #else
 #    if defined(USE_GPIOV1)
-#        define WS2812_OUTPUT_MODE PAL_MODE_ALTERNATE_PUSHPULL
+#        define WS2812_OUTPUT_MODE PAL_MODE_ALTERNATE_OPENDRAIN
 #    else
 #        define WS2812_OUTPUT_MODE PAL_MODE_ALTERNATE(WS2812_PWM_PAL_MODE) | PAL_OUTPUT_TYPE_OPENDRAIN | PAL_OUTPUT_SPEED_HIGHEST | PAL_PUPDR_FLOATING
 #    endif