media: uvcvideo: Provide sync and async uvc_ctrl_status_event

Split the functionality of void uvc_ctrl_status_event_work in two, so it
can be called by functions outside interrupt context and not part of an
URB.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>