Add new subtest to video_device_test to cover the VIDIOC_G_PRIORITY
and VIDIOC_S_PRIORITY ioctl calls. This test tries to set the priority
associated with the file descriptior via ioctl VIDIOC_S_PRIORITY
command from V4L2 API. After that, the test tries to get the new
priority via VIDIOC_G_PRIORITY ioctl command and compares the result
with the v4l2_priority it set before. At the end, the test restores the
old priority.

This test will increase the code coverage for video_device_test, so
I think it might be useful. Additionally, this patch will refactor the
video_device_test a little bit, according to the new functionality.

Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Replace GPL license statement with SPDX GPL-2.0 license identifier.

Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>

Add a new video device test that opens user specified Video Device and
calls video ioctls in a loop once every 10 seconds.

This test is intended for testing device removal and driver unbind while
an ioctl is active. Clean device removal and driver unbind is expected
without any use-after-free and panics.

Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>