MAINTAINERS: Update VT-d entry for drivers/pci -> drivers/iommu move

Commit 166e9278 ("x86/ia64: intel-iommu: move to drivers/iommu/")
moved the VT-d driver to drivers/iommu, but left the "F:" line in
MAINTAINERS pointing to drivers/pci, which breaks scripts/get_maintainer.pl.
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

MAINTAINERS

@@ -3313,7 +3313,7 @@ M:	David Woodhouse <dwmw2@infradead.org>
 L:	iommu@lists.linux-foundation.org
 T:	git git://git.infradead.org/iommu-2.6.git
 S:	Supported
-F:	drivers/pci/intel-iommu.c
+F:	drivers/iommu/intel-iommu.c
 F:	include/linux/intel-iommu.h
 
 INTEL IOP-ADMA DMA DRIVER