media: staging: rkisp1: improve documentation in file rkisp1-config.h

There is some missing documentation of structs and
fields in rkisp1-config.h. This patch improves the
documentation.

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>