staging: hikey9xx: add a TODO list

Place the things that are needed to be able to move those
drivers out of staging.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/bf3ebe32125646e0a87a59280392e8c6fda08488.1597647359.git.mchehab+huawei@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>