media: atomisp: add a way for the driver to know the chipset version

The atomisp supports two different chipsets: ISP2400 and ISP2401.
Right now, this is controlled by ugly #defines inside the driver.

Add a global bolean to identify the type of hardware. While this
is hacky, it would be a quick way to start removing the ugly
ifdefs.

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