x86, AMD IOMMU: add Kconfig entry

This patch adds the Kconfig entry for the AMD IOMMU driver.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Cc: iommu@lists.linux-foundation.org
Cc: bhavna.sarathy@amd.com
Cc: Sebastian.Biemueller@amd.com
Cc: robert.richter@amd.com
Cc: joro@8bytes.org
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/Kconfig

@@ -549,6 +549,13 @@ config CALGARY_IOMMU_ENABLED_BY_DEFAULT
 	  Calgary anyway, pass 'iommu=calgary' on the kernel command line.
 	  If unsure, say Y.
 
+config AMD_IOMMU
+	bool "AMD IOMMU support"
+	select SWIOTL
+	depends on X86_64 && PCI
+	help
+	  Select this to get support for AMD IOMMU hardware in your system.
+
 # need this always selected by IOMMU for the VIA workaround
 config SWIOTLB
 	bool