Revert "x86: blacklist DMAR on Intel G31/G33 chipsets"

This reverts commit e51af6630848406fc97adbd71443818cdcda297b, which was
wrongly hoovered up and submitted about a month after a better fix had
already been merged.

The better fix is commit cbda1ba898647aeb4ee770b803c922f595e97731
("PCI/iommu: blacklist DMAR on Intel G31/G33 chipsets"), where we do
this blacklisting based on the DMI identification for the offending
motherboard, since sometimes this chipset (or at least a chipset with
the same PCI ID) apparently _does_ actually have an IOMMU.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>