media: atmel: atmel-isc: add CC initialization function

The CC submodule is a part of the atmel-isc pipeline, and stands for
Color Correction. It is used to apply gains and offsets to the
chroma (U, V) components of the YUV elements.
Implement the CC submodule initialization, as a product
specific function, which currently configures the neutral point in color
correction.

[hverkuil: made isc_sama5d2_config_cc static]

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>