x86-64: enable sg chaining

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

include/asm-x86/dma-mapping_64.h

@@ -6,8 +6,7 @@
  * documentation.
  */
 
-
-#include <asm/scatterlist.h>
+#include <linux/scatterlist.h>
 #include <asm/io.h>
 #include <asm/swiotlb.h>
 

include/asm-x86/scatterlist_64.h

@@ -11,6 +11,8 @@ struct scatterlist {
     unsigned int        dma_length;
 };
 
+#define ARCH_HAS_SG_CHAIN
+
 #define ISA_DMA_THRESHOLD (0x00ffffff)
 
 /* These macros should be used after a pci_map_sg call has been done