[media] atomisp: disable several warnings when W=1

The atomisp currently produce hundreds of warnings when W=1.

It is a known fact that this driver is currently in bad
shape, and there are lot of things to be done here.

We don't want to be bothered by those "minor" stuff for now,
while the driver doesn't receive a major cleanup. So,
disable those warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>