usb: gadget: uvc: Factor out video USB request queueing

usb: gadget: uvc: Factor out video USB request queueing

[ Upstream commit 9d1ff5dcb3cd3390b1e56f1c24ae42c72257c4a3 ]

USB requests for video data are queued from two different locations in
the driver, with the same code block occurring twice. Factor it out to a
function.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Tested-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>