media: atomisp: Mark ia_css_isys_240?_init() static

media: atomisp: Mark ia_css_isys_240?_init() static

ia_css_isys_240?_init() are only used inside the C file where they are
declared, mark them as static fixing:

drivers/staging/media/atomisp/pci/runtime/isys/src/isys_init.c:24:20:
   warning: no previous prototype for 'ia_css_isys_2400_init'
   24 | input_system_err_t ia_css_isys_2400_init(void)
      |                    ^~~~~~~~~~~~~~~~~~~~~
drivers/staging/media/atomisp/pci/runtime/isys/src/isys_init.c:87:20:
   warning: no previous prototype for 'ia_css_isys_2401_init'
   87 | input_system_err_t ia_css_isys_2401_init(void)
      |                    ^~~~~~~~~~~~~~~~~~~~~

Closes: https://lore.kernel.org/oe-kbuild-all/202307152046.rvhFGrbz-lkp@intel.com/
Link: https://lore.kernel.org/r/20230715170906.3627-3-hdegoede@redhat.com
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Kate Hsuan <hpa@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>