media: uvcvideo: Allow entity-defined get_info and get_cur

[ Upstream commit 65900c581d014499f0f8ceabfc02c652e9a88771 ]

Allows controls to get their properties and current value
from an entity-defined function instead of via a query to the USB
device.

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>
Stable-dep-of: 86419686e66d ("media: uvcvideo: Override default flags")
Signed-off-by: Sasha Levin <sashal@kernel.org>