media: atomisp: make all file names unique at atomisp driver

The *system_*.h files contain ISP-specific definitions, and are
used everywhere.

While the best would be to get rid of those in favor of some
ISP-specific structs, a change like that would require lots
of changes.

So, instead, let's rename those files replacing them by new
ones with ISP ifdefs on it, in order to select between the
two different versions.

We shall later convert this to some abrstraction layer,
but this change should help to be able to build support for
either ISP2400 or ISP2401.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>