gma500: More Moorestown muddle meddling means MM maybe might modeset

There are a least three different species we need to deal with and right
now it seems the only way to sort them out is via DMI. Encapsulate the
entire pile somewhere private and out of the way.

Hopefully a saner method will emerge later.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>