media: atomisp: get rid of an iomem abstraction layer

The hive_isp_css_custom_host_hrt.h code, together
with atomisp_helper.h, provides an abstraction layer for
some functions inside atomisp_compat_css20.c and atomisp_cmd.c.

There's no good reason for that. In a matter of fact, after
removing the abstraction, the code looked a lot cleaner
and easier to understand.

So, get rid of them.

While here, get rid also of the udelay(1) abstraction code.

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

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: get rid of an error abstraction layer

There is an abstraction layer there meant to convert to
the Linux standard error codes. As the driver now use
such errors everywhere. we can get rid of this.

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>