[media] media: am437x: Don't release OF node reference twice

The remote port reference is released both at the end of the OF graph
parsing loop, and in the error code path at the end of the function.
Those two calls will release the same reference, causing the reference
count to go negative.

Fix the problem by removing the second call.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Acked-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>