leds: Make flash and multicolor dependencies unconditional

Along the same lines as making devm_led_classdev_register() declared
extern unconditional, do the same thing for the two sub-classes
that have similar stubs.

The users of these interfaces go to great lengths to allow building
with both the generic leds API and the extended version, but realistically
there is not much use in this, so just simplify it to always rely
on it and remove the confusing fallback logic.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20240109090715.982332-2-arnd@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

leds: flash: Fix multicolor no-ops registration by return 0

Fix multicolor no-ops registration by return 0,
and move the same registration functions outside of #ifdef block.

Signed-off-by: Gene Chen <gene_chen@richtek.com>
Acked-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

leds: multicolor: Introduce a multicolor class definition

Introduce a multicolor class that groups colored LEDs
within a LED node.

The multicolor class groups monochrome LEDs and allows controlling two
aspects of the final combined color: hue and lightness. The former is
controlled via the intensity file and the latter is controlled
via brightness file.

Signed-off-by: Dan Murphy <dmurphy@ti.com>
Acked-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
[squashed leds: multicolor: Fix camel case in documentation in]