leds: led-core: Fix refcount leak in of_led_get()

class_find_device_by_of_node() calls class_find_device(), it will take
the reference, use the put_device() to drop the reference when not need
anymore.

Fixes: 699a8c7c ("leds: Add of_led_get() and led_put()")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20221220121807.1543790-1-linmq006@gmail.com