media: staging: rkisp1: isp: set metadata pads to MEDIA_BUS_FMT_METADATA_FIXED

Set the code of the metadata pads of the isp entity to
MEDIA_BUS_FMT_METADATA_FIXED and set the width and
height of their formats to 0. This solves the TODO
item:
"Fix pad format size for statistics and parameters entities."

Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Acked-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>