media: stkwebcam: use u64 for the timestamp internally

Just like vb2 does, use u64 internally to store the timestamps
of the buffers. Only convert to timeval when interfacing with
userspace.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/usb/stkwebcam/stk-webcam.c

@@ -1144,7 +1144,7 @@ static int stk_vidioc_dqbuf(struct file *filp,
 	sbuf->v4lbuf.flags &= ~V4L2_BUF_FLAG_QUEUED;
 	sbuf->v4lbuf.flags |= V4L2_BUF_FLAG_DONE;
 	sbuf->v4lbuf.sequence = ++dev->sequence;
-	v4l2_get_timestamp(&sbuf->v4lbuf.timestamp);
+	sbuf->v4lbuf.timestamp = ns_to_timeval(ktime_get_ns());
 
 	*buf = sbuf->v4lbuf;
 	return 0;