iommu/dma: Tidy up Kconfig selects

Now that the dust has settled on converting all the x86 drivers to
iommu-dma, we can punt the Kconfig selection to arch code where it
was always intended to be.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>

arch/ia64/Kconfig

@@ -51,6 +51,7 @@ config IA64
 	select GENERIC_TIME_VSYSCALL
 	select LEGACY_TIMER_TICK
 	select SWIOTLB
+	select IOMMU_DMA if INTEL_IOMMU
 	select SYSCTL_ARCH_UNALIGN_NO_WARN
 	select HAVE_MOD_ARCH_SPECIFIC
 	select MODULES_USE_ELF_RELA

arch/x86/Kconfig

@@ -247,6 +247,7 @@ config X86
 	select HAVE_USER_RETURN_NOTIFIER
 	select HAVE_GENERIC_VDSO
 	select HOTPLUG_SMT			if SMP
+	select IOMMU_DMA			if IOMMU_SUPPORT
 	select IRQ_FORCED_THREADING
 	select NEED_SG_DMA_LENGTH
 	select PCI_DOMAINS			if PCI

drivers/iommu/Kconfig

@@ -459,7 +459,6 @@ config VIRTIO_IOMMU
 	depends on VIRTIO
 	depends on (ARM64 || X86)
 	select IOMMU_API
-	select IOMMU_DMA
 	select INTERVAL_TREE
 	select ACPI_VIOT if ACPI
 	help

drivers/iommu/amd/Kconfig

@@ -9,7 +9,6 @@ config AMD_IOMMU
 	select PCI_PASID
 	select IOMMU_API
 	select IOMMU_IOVA
-	select IOMMU_DMA
 	select IOMMU_IO_PGTABLE
 	depends on X86_64 && PCI && ACPI && HAVE_CMPXCHG_DOUBLE
 	help

drivers/iommu/intel/Kconfig

@@ -16,7 +16,6 @@ config INTEL_IOMMU
 	select DMAR_TABLE
 	select SWIOTLB
 	select IOASID
-	select IOMMU_DMA
 	select PCI_ATS
 	help
 	  DMA remapping (DMAR) devices support enables independent address