media: stm32-dcmi: Delete an unnecessary of_node_put() call in dcmi_probe()

A null pointer would be passed to a call of the function “of_node_put”
immediately after a call of the function “of_graph_get_next_endpoint”
failed at one place.
Remove this superfluous function call.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>