mb/*/*: Enable libgfxinit on x4x boards

TESTED Intel DG41WV with VGA, Intel DG43GT with VGA and HDMI1 and
HDMI2.

Change-Id: I774b79cc0ef9dc72ccf48901ab94376b27ed9c7a
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/26966
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
15 files changed