media: staging: rkisp1: replace 9 coeff* fields with a 3x3 array

The struct rkisp1_cif_isp_ctk_config has 9 fields 'coeff*' for the
3x3 color correction matrix. Replace these fields with one 3x3
array coeff[3][3] and document the field.

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>