media: davinci-vpif: Don't dereference endpoint after putting it, fix refcounting

The davinci-vpif driver dereferences its local endpoints after releasing
the reference to them.

The driver also puts its endpoints explicitly while the
of_graph_get_next_endpoint() does that, too, leading to obtaining a
reference once and releasing it twice.

Both are fixed by this patch.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>