media: atomisp: Remove unused declarations

There is a few static declarations that are not used anywhere, remove them.

Link: https://lore.kernel.org/linux-media/20210526124322.48915-3-andriy.shevchenko@linux.intel.com


Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>