media: uvcvideo: Refactor uvc_queue_streamon

Do uvc_pm_get before we call uvc_queue_streamon. Although the current
code is correct, uvc_ioctl_streamon is allways called after uvc_pm_get,
this change makes the code more resiliant to future changes.

Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20250509-uvc-followup-v1-2-73bcde30d2b5@chromium.org


Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>