dri: Move driver config options to dri driver extensions.

dri: Move driver config options to dri driver extensions.

This way they aren't all sitting in the global namespace (with the same
name per driver).

Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Chad Versace <chad.versace@linux.intel.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>