MAINTAINERS: add entry for ARM system MMU driver

Add myself as maintainer for the ARM system MMU driver.
Acked-by: NGrant Likely <grant.likely@secretlab.ca>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NJoerg Roedel <joro@8bytes.org>

MAINTAINERS

@@ -1310,6 +1310,12 @@ T:	git git://git.xilinx.com/linux-xlnx.git
 S:	Supported
 F:	arch/arm/mach-zynq/
 
+ARM SMMU DRIVER
+M:	Will Deacon <will.deacon@arm.com>
+L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
+S:	Maintained
+F:	drivers/iommu/arm-smmu.c
+
 ARM64 PORT (AARCH64 ARCHITECTURE)
 M:	Catalin Marinas <catalin.marinas@arm.com>
 M:	Will Deacon <will.deacon@arm.com>