leds: Fix leds_list_lock locking issues

Covert leds_list_lock to a rw_sempahore to match previous LED trigger
locking fixes, fixing lock ordering.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>

diff --cc drivers/leds/led-class.c
Simple merge

diff --cc drivers/leds/led-core.c
Simple merge

diff --cc drivers/leds/led-triggers.c
Simple merge

diff --cc drivers/leds/leds.h
Simple merge