media: rockchip: rkisp1: Mask invalid bits in DPCC parameters

Restrict the DPCC configuration that can be set by userspace to valid
register bits. To do so, reorganize the related register macros to
define valid bitmasks, as well as bits of the DPCC mode register.

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