fbd-dev-led: Rework color API

Drop has_color API since supported colors are set during probing
and can be handled completely separately from the classes for
each type of hardware.

Rename set_color to set_supported_color because the usage
of this API is to check if the color is supported, but not
setting it. Setting the color is also separated from
start_periodic API to re-use multicolor across multiple LED types
with a set_color API. Multicolor LEDs are actually the same as
regular LEDs but they require a few additional sysfs entries to
actually set the color. Single color LEDs only have a single color
so the set_color method just returns TRUE for these LEDs.

Supported colors are advertised through the supports_color API now.
This way, each LED driver define which colors are supported
through supports_color API. RGB multicolor LEDs will report only fixed colors
like red, blue, green and white until the kernel can expose if a diffusor
is present to mix these colors.

src/fbd-dev-led-priv.h

@@ -17,6 +17,6 @@ G_BEGIN_DECLS
 
 GUdevDevice      *fbd_dev_led_get_device  (FbdDevLed *led);
 void              fbd_dev_led_set_max_brightness (FbdDevLed *led, guint max_brightness);
-void              fbd_dev_led_set_color (FbdDevLed *led, FbdFeedbackLedColor color);
+void              fbd_dev_led_set_supported_color (FbdDevLed *led, FbdFeedbackLedColor color);
 
 G_END_DECLS