dma-mapping: move all DMA mapping code to kernel/dma

Currently the code is split over various files with dma- prefixes in the
lib/ and drives/base directories, and the number of files keeps growing.
Move them into a single directory to keep the code together and remove
the file name prefixes.  To match the irq infrastructure this directory
is placed under the kernel/ directory.

Signed-off-by: Christoph Hellwig <hch@lst.de>

lib/Kconfig

@@ -420,60 +420,15 @@ config HAS_IOPORT_MAP
 	depends on HAS_IOMEM && !NO_IOPORT_MAP
 	default y
 
-config HAS_DMA
-	bool
-	depends on !NO_DMA
-	default y
+source "kernel/dma/Kconfig"
 
 config SGL_ALLOC
 	bool
 	default n
 
-config NEED_SG_DMA_LENGTH
-	bool
-
-config NEED_DMA_MAP_STATE
-	bool
-
-config ARCH_DMA_ADDR_T_64BIT
-	def_bool 64BIT || PHYS_ADDR_T_64BIT
-
 config IOMMU_HELPER
 	bool
 
-config ARCH_HAS_SYNC_DMA_FOR_DEVICE
-	bool
-
-config ARCH_HAS_SYNC_DMA_FOR_CPU
-	bool
-	select NEED_DMA_MAP_STATE
-
-config DMA_DIRECT_OPS
-	bool
-	depends on HAS_DMA
-
-config DMA_NONCOHERENT_OPS
-	bool
-	depends on HAS_DMA
-	select DMA_DIRECT_OPS
-
-config DMA_NONCOHERENT_MMAP
-	bool
-	depends on DMA_NONCOHERENT_OPS
-
-config DMA_NONCOHERENT_CACHE_SYNC
-	bool
-	depends on DMA_NONCOHERENT_OPS
-
-config DMA_VIRT_OPS
-	bool
-	depends on HAS_DMA
-
-config SWIOTLB
-	bool
-	select DMA_DIRECT_OPS
-	select NEED_DMA_MAP_STATE
-
 config CHECK_SIGNATURE
 	bool