media: v4l: vsp1: Add BRx dynamic assignment debugging messages

Dynamic assignment of the BRU and BRS to pipelines is prone to
regressions, add messages to make debugging easier. Keep it as a
separate commit to ease removal of those messages once the code will
deem to be completely stable.

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