leds: Add basic support for TI/National Semiconductor LP5812 LED Driver

leds: Add basic support for TI/National Semiconductor LP5812 LED Driver

The LP5812 is a 4x3 matrix RGB LED driver with an autonomous animation
engine and time-cross-multiplexing (TCM) support for up to 12 LEDs or
4 RGB LEDs. Each LED can be configured through the related registers
to realize vivid and fancy lighting effects.

This patch adds minimal driver support for the LP5812, implementing
only the essential functionality: I2C communication with the device,
LED registration, brightness control in manual mode, and basic sysfs
interfaces for LED configuration and fault monitoring.

Signed-off-by: Nam Tran <trannamatk@gmail.com>
Link: https://patch.msgid.link/20260115161013.40706-2-trannamatk@gmail.com
Signed-off-by: Lee Jones <lee@kernel.org>