staging: vc04_services: Add outstanding VCHI TODOs

The TODO list missed some issues before we can move the driver out of staging.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>