intel/gm45: native gfx init.

Tested on lenovo X200 in both text and gfx mode.

Change-Id: I273971d0f34ca3529959d4228e9516775459b806
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: http://review.coreboot.org/6682
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>