media: davinci: vpif: add missing of_node_put() in vpif_probe()

of_graph_get_next_endpoint() returns an 'endpoint' node pointer
with refcount incremented. The refcount should be decremented
before returning from vpif_probe().

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>