drm: rcar-du: Support up to 4 CRTCs

The Gen3 R8A7795 DU has 4 CRTCs, support them all.

Signed-off-by: Koji Matsuoka <koji.matsuoka.xm@renesas.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
3 files changed