[media] media: platform: ti-vpe: call of_node_put on non-null pointer

It should call of_node_put on non-null poiner.

Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Peter Chen <peter.chen@nxp.com>
Acked-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>