media: staging: atomisp: Remove driver

The atomisp driver has a long list of todo items and little has been done
to address these lately while more has been added. The driver is also not
functional. In other words, the driver would not be getting out of staging
in the foreseeable future. At the same time it consumes developer
resources in order to maintain the flaky code base. Remove it.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>