nb/intel/x4x: Don't run NGI if IGD has not been assigned VGA cycles

The NGI writes to legacy VGA registers which should not happen when
VGA cycles are assigned to a different device.

TESTED on ga-g41m-es2l

Change-Id: I0a03e35c0d7f2532edd6cc5e62d1cf07dab57f60
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/19607
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
1 file changed