media: rkisp1: debug: Add dump file in debugfs for MI main path registers

Add a register dump file in debugfs for some of the buffer-related
registers for the main path in MI (for the base address, the size, and
the offset). Also dump the corresponding shadow registers.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Dafna Hirschfeld <dafna@fastmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>