media: exynos4-is: add missing call to of_node_put()

In one of the error paths of the for_each_child_of_node() loop in
fimc_md_parse_one_endpoint, add missing call to of_node_put().

Fix the following coccicheck warning:
./drivers/media/platform/exynos4-is/media-dev.c:489:1-23: WARNING:
Function "for_each_child_of_node" should have of_node_put() before
return around line 492.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>