add AMD IOMMU tree to MAINTAINERS file

Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

MAINTAINERS

@@ -387,6 +387,7 @@ AMD IOMMU (AMD-VI)
 P:	Joerg Roedel
 M:	joerg.roedel@amd.com
 L:	iommu@lists.linux-foundation.org
+T:	git://git.kernel.org/pub/scm/linux/kernel/git/joro/linux-2.6-iommu.git
 S:	Supported
 
 AMS (Apple Motion Sensor) DRIVER