dma-mapping: split <linux/dma-mapping.h>

Split out all the bits that are purely for dma_map_ops implementations
and related code into a new <linux/dma-map-ops.h> header so that they
don't get pulled into all the drivers.  That also means the architecture
specific <asm/dma-mapping.h> is not pulled in by <linux/dma-mapping.h>
any more, which leads to a missing includes that were pulled in by the
x86 or arm versions in a few not overly portable drivers.

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

arch/x86/kernel/setup.c

@@ -7,6 +7,7 @@
  */
 #include <linux/console.h>
 #include <linux/crash_dump.h>
+#include <linux/dma-contiguous.h>
 #include <linux/dmi.h>
 #include <linux/efi.h>
 #include <linux/init_ohci1394_dma.h>
@@ -19,6 +20,7 @@
 #include <linux/hugetlb.h>
 #include <linux/tboot.h>
 #include <linux/usb/xhci-dbgp.h>
+#include <linux/swiotlb.h>
 
 #include <uapi/linux/mount.h>