drivers/video/backlight/88pm860x_bl.c: add missing of_node_put()

of_find_node_by_name() returns a node pointer with refcount incremented,
use of_node_put() on it when done.

of_find_node_by_name() will call of_node_put() against the node pass to
from parameter, thus we also need to call of_node_get(from) before calling
of_find_node_by_name().

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Cc: Jingoo Han <jg1.han@samsung.com>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>