media: rkisp1: isp: Pass rkisp1_isp pointer to internal ISP functions

Replace the rkisp1_device pointer argument to the internal functions of
the ISP implementation with a rkisp1_isp object. This makes the code
flow more logical, as the functions operate on the ISP object.

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