leds: lp8860: Disable GPIO with devm action

This helps prevent mistakes like disable out of order in cleanup functions
and forgetting to free on error paths (as was done here).

This was the last thing the .remove() function did, so remove that too.

Signed-off-by: Andrew Davis <afd@ti.com>
Link: https://lore.kernel.org/r/20250407183555.409687-6-afd@ti.com


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