hp/pavilion_m6_1035dx: Enable IOMMU

Change-Id: Ia14490c9074d35b7dde99e38b4ee169d4e4589a4
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/7678
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>