dt-bindings: leds: sgm3140: Document richtek,rt5033 compatible

Add devicetree binding for Richtek RT5033 Flash LED charge pump used for
camera flash LEDs.

Signed-off-by: Raymond Hackley <raymondhackley@protonmail.com>
Link: https://lore.kernel.org/r/20230602131009.260239-1-raymondhackley@protonmail.com


Signed-off-by: Lee Jones <lee@kernel.org>