media: atomisp: Update TODO

A lot of work has been done on the atomisp driver lately.

Rewrite the TODO file to drop all the already fixed items:

* Moved to videobuf2 + fixed mmap support
* Whole bunch of v4l2 API fixes making more apps work
* v4l2-async sensor probing support
* pm-runtime support (for some sensor drivers at least)
* buffer MM code was cleaned up / replaced when moving the videobuf2

And add a new TODO list (retaining some of the old items) split
into items which absolutely must be fixed before the driver can
be moved out of staging:

1. Conflicting hw-ids with regular sensor drivers
2. Private userspace API stuff

As well as a list of items which also definitely needs to be fixed
but which could also be fixed after moving the driver out of staging.

Link: https://lore.kernel.org/r/20230529103741.11904-2-hdegoede@redhat.comSigned-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>