media: rockchip: rkisp1: Define macros for DPCC configurations in UAPI

Extend the UAPI rkisp1-config.h header with macros for all DPCC
configuration fields. While at it, clarify of fix issues in the DPCC
documentation.

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>