[media] v4l: vsp1: Set the SRU CTRL0 register when starting the stream

Commit 58f896d8 ("[media] v4l: vsp1: sru: Make the intensity
controllable during streaming") refactored the stream start code and
removed the SRU CTRL0 register write by mistake. Add it back.

Fixes: 58f896d8 ("[media] v4l: vsp1: sru: Make the intensity controllable during streaming")

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