If the SoC is VT-d capable, write an ACPI DMAR table. The entry for the GFXVTBAR is only generated if the IGD is enabled. Change-Id: Id7c899954f1bae9d2b48532ca5ee271944f0c5f6 Signed-off-by: Matt DeVillier <matt.devillier@gmail.com> Reviewed-on: https://review.coreboot.org/23821 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Youness Alaoui <snifikino@gmail.com> Reviewed-by: Nico Huber <nico.h@gmx.de>