media: test-drivers: vivid: don't call schedule in loop

Artem reported that the CPU load was 100% when capturing from
vivid at low resolution with ffmpeg.

This was caused by:

while (time_is_after_jiffies(cur_jiffies + wait_jiffies) &&
       !kthread_should_stop())
        schedule();

If there are no other processes running that can be scheduled,
then this is basically a busy-loop.

Change it to wait_event_interruptible_timeout() which doesn't
have that problem.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Reported-by: Artem S. Tashkinov <aros@gmx.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219570


Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>