leds: qcom-lpg: Use devm_pwmchip_add() simplifying driver removal

With pwmchip_remove() being automatically called after switching to
devm_pwmchip_add() the remove function can be dropped completely. Yay!
With lpg_remove() gone there is no user of the platform device's drvdata
left, so platform_set_drvdata() can be dropped from .probe(), too.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20231126095230.683204-2-u.kleine-koenig@pengutronix.de


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