leds: Convert all platform drivers to return void

leds: Convert all platform drivers to return void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.
To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new() which already returns void. Eventually after all drivers
are converted, .remove_new() is renamed to .remove().

All platform drivers below drivers/leds/ unconditionally return zero in
their remove callback and so can be converted trivially to the variant
returning void.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230917130947.1122198-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Lee Jones <lee@kernel.org>