media: platform: mtk-mdp: mtk_mdp_core: Add of_node_put() before goto

Each iteration of for_each_child_of_node puts the previous node, but in
the case of a goto from the middle of the loop, there is no put, thus
causing a memory leak. Hence add an of_node_put before the goto in two
places.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Acked-by: Houlong Wei <houlong.wei@mediatek.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>