leds: leds-mt6323: Add support for WLEDs and MT6332

Add basic code to turn on and off WLEDs and wire up MT6332 support
to take advantage of it.
This is a simple approach due to the aforementioned PMIC supporting
only on/off status so, at the time of writing, it is impossible for me
to validate more advanced functionality due to lack of hardware.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230601110813.2373764-9-angelogioacchino.delregno@collabora.com