media: vsp1: vsp1_dl: Count display lists

To detect leaks of display lists, store in the display list manager the
number of allocated display lists when the manager is created and verify
that when the display manager is reset the same number of lists is
available in the free list.

Signed-off-by: Jacopo Mondi <jacopo.mondi+renesas@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Link: https://lore.kernel.org/r/20250616-vsp1_dl_list_count-v2-2-7d3f43fb1306@ideasonboard.com


Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>