select IOMMU_API when DMAR and/or AMD_IOMMU is selected

These two IOMMUs can implement the current version of this API. So
select the API if one or both of these IOMMU drivers is selected.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

arch/ia64/Kconfig

@@ -687,3 +687,6 @@ config IRQ_PER_CPU
 
 config IOMMU_HELPER
 	def_bool (IA64_HP_ZX1 || IA64_HP_ZX1_SWIOTLB || IA64_GENERIC || SWIOTLB)
+
+config IOMMU_API
+	def_bool (DMAR)

arch/x86/Kconfig

@@ -599,6 +599,9 @@ config SWIOTLB
 config IOMMU_HELPER
 	def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
 
+config IOMMU_API
+	def_bool (AMD_IOMMU || DMAR)
+
 config MAXSMP
 	bool "Configure Maximum number of SMP Processors and NUMA Nodes"
 	depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL

drivers/base/Makefile

@@ -11,6 +11,7 @@ obj-$(CONFIG_FW_LOADER)	+= firmware_class.o
 obj-$(CONFIG_NUMA)	+= node.o
 obj-$(CONFIG_MEMORY_HOTPLUG_SPARSE) += memory.o
 obj-$(CONFIG_SMP)	+= topology.o
+obj-$(CONFIG_IOMMU_API) += iommu.o
 ifeq ($(CONFIG_SYSFS),y)
 obj-$(CONFIG_MODULES)	+= module.o
 endif