media: atomisp: add SPDX headers

This driver is licensed under GPL 2.0, as stated inside their
headers.

Add the proper tag there. We should probably latter cleanup
the reduntant licensing text, but this could be done later,
after we get rid of other abstraction layers.

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

media: atomisp: remove some trivial wrappers from compat css20

There are tons of code inside atomisp_compat_css20.c, but
several of them are just trivial wrappers to other functions.

Getting rid of all of them will take some time, but let's
start getting rid of some of the trivial ones.

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

media: atomisp: get rid of memory_access.c

Now that we have everything in place, we can get rid of the
memory_access abstraction layer.

Now, everything related to heterogeneous memory management
(hmm) is under hmm.c & related pools.

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

media: atomisp: cleanup directory hierarchy

This driver has very long directories without a good
reason (IMHO). Let's drop two directories from such hierarchy,
in order to simplify things a little bit and make the dir
output a bit more readable.

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