[media] v4l: vsp1: Add support for the R-Car Gen3 VSP2

Add DT compatible strings for the VSP2 instances found in the R-Car Gen3
SoCs and support them in the vsp1 driver.

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