[media] v4l: vsp1: sru: Fix intensity control ID

The intensity control reused the V4L2_CID_CONTRAST control ID by
mistake. Fix it by using an ID from the device-specific IDs range.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>