media: v4l: vsp1: Add per-display list internal completion notification support

Display list completion is already reported to the frame end handler,
but that mechanism is global to all display lists. In order to implement
BRU and BRS reassignment in DRM pipelines we will need to commit a
display list and wait for its completion internally, without reporting
it to the DRM driver. Extend the display list API to support such an
internal use of the display list.

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