media: staging: atomisp: gc2235: fix sparse warning: missing static

Several local use structs were missing declarations. Added static
qualifier to clean up Sparse warning.

Signed-off-by: Guillermo O. Freschi <kedrot@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>