media: staging: rkisp1: isp: do not set invalid mbus code for pad

When setting source pad, check if the given mbus code is indeed valid
for source pad, if not, then set the default code.
Same for sink pad.

Fixes: d65dd852 ("media: staging: rkisp1: add Rockchip ISP1 base driver")
Reported-by: Wojciech Zabolotny <wzab01@gmail.com>
Signed-off-by: Helen Koike <helen.koike@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>