If v4l2_ctrl_next is called without the V4L2_CTRL_FLAG_NEXT_CTRL then it
should check whether the passed control ID is valid and return 0 if it
isn't. Otherwise a for-loop over the control IDs will never end.

(cherry picked from commit a46c5fbc)
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>