media: atmel: atmel-isc: create callback for DPC submodule product specific

The DPC submodule is a part of the atmel-isc pipeline, and stands for
Defective Pixel Correction. Its purpose is to detect defective pixels and
correct them if possible with the help of adjacent pixels.
Create a product specific callback for initializing the DPC submodule
of the pipeline.
For sama5d2 product, this module does not exist, thus this function is a noop.

[hverkuil: made isc_sama5d2_config_dpc 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>