AMD IOMMU: add MSI interrupt support

The AMD IOMMU can generate interrupts for various reasons. This patch
adds the basic interrupt enabling infrastructure to the driver.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ed92864..39fd3f4 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -553,6 +553,7 @@
 config AMD_IOMMU
 	bool "AMD IOMMU support"
 	select SWIOTLB
+	select PCI_MSI
 	depends on X86_64 && PCI && ACPI
 	help
 	  With this option you can enable support for AMD IOMMU hardware in