dma-mapping: make the generic coherent dma mmap implementation optional

This series converts all remaining architectures to use dma_map_ops and
the generic implementation of the DMA API.  This not only simplifies the
code a lot, but also prepares for possible future changes like more
generic non-iommu dma_ops implementations or generic per-device
dma_map_ops.

This patch (of 16):

We have a couple architectures that do not want to support this code, so
add another Kconfig symbol that disables the code similar to what we do
for the nommu case.

Signed-off-by: Christoph Hellwig <[email protected]>
Cc: Haavard Skinnemoen <[email protected]>
Cc: Hans-Christian Egtvedt <[email protected]>
Cc: Steven Miao <[email protected]>
Cc: Ley Foon Tan <[email protected]>
Cc: David Howells <[email protected]>
Cc: Koichi Yasutake <[email protected]>
Cc: Chris Metcalf <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Aurelien Jacquiot <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: James Hogan <[email protected]>
Cc: Jesper Nilsson <[email protected]>
Cc: Mark Salter <[email protected]>
Cc: Mikael Starvik <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Sebastian Ott <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

arch/Kconfig

@@ -632,4 +632,7 @@ config OLD_SIGACTION
 config COMPAT_OLD_SIGACTION
 	bool
 
+config ARCH_NO_COHERENT_DMA_MMAP
+	bool
+
 source "kernel/gcov/Kconfig"