media: uvcvideo: Fix annotation for uvc_video_clock_update()

The formula (2) is to convert from SOF to host clock,
it should be fix as
"TS = ((TS2 - TS1) * SOF + TS1 * SOF2 - TS2 * SOF1) / (SOF2 - SOF1)"

Signed-off-by: Jun Chen <jun.chen@vatics.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>