[media] exynos4-is: Put node before s5pcsis_parse_dt() return error

The MIPI CSIS DT parse function return an -ENXIO errno if the port #
is outside of the supported values. But it doesn't call of_node_put()
to decrement the node's reference counter, that's incremented inside
the of_graph_get_next_endpoint() function that was called before.

Instead of just returning, go to the error path that already does it.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>