media: vsp1: drm: Extend frame completion API to the DU driver

The VSP1 driver will need to pass extra flags to the DU through the
frame completion API. Replace the completed bool flag by a bitmask to
support this.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>