media: xilinx-video: fix bad of_node_put() on endpoint error

When iterating through all endpoints using of_graph_get_next_endpoint(),
the refcount of the returned endpoint node is incremented and the refcount
of the node which is passed as previous endpoint is decremented.

So the caller doesn't need to call of_node_put() for each iterated node
except for error exit paths.  Otherwise we get "OF: ERROR: Bad
of_node_put() on ..." messages.

Cc: Hyun Kwon <hyun.kwon@xilinx.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>