gma500: initial medfield merge

We need to merge this ahead of some of the cleanup because a lot of needed
cleanup spans both new and old chips. If we try and clean up and the merge
we end up fighting ourselves.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[With a load of the cleanup stuff folded in, register stuff reworked sanely]
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>