staging: media: atomisp: Disallow all private IOCTLs

staging: media: atomisp: Disallow all private IOCTLs

Disallow all private IOCTLs. These aren't quite as safe as one could
assume of IOCTL handlers; disable them for now. Instead of removing the
code, return in the beginning of the function if cmd is non-zero in order
to keep static checkers happy.

Reported-by: Soufiane Dani <soufianeda@tutanota.com>
Closes: https://lore.kernel.org/linux-staging/20260210-atomisp-fix-v1-1-024429cbff31@tutanota.com/
Cc: stable@vger.kernel.org
Fixes: a49d25364dfb ("staging/atomisp: Add support for the Intel IPU v2")
Fixes: ad85094b293e ("Revert "media: staging: atomisp: Remove driver"")
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>