media: atomisp: go one step further to drop ia_css_memory_access.c

Move the attrs handling into hmm, simplifying even further
what the ia_css_memory_access.c file does.

Yet, the returned type for ia_css_memory_access.c is an
integer, instead of a pointer.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>