x86: move dma_unmap_sg to common header

i386 gets an empty function.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/include/asm-x86/dma-mapping.h b/include/asm-x86/dma-mapping.h
index 0901154..6e7747a 100644
--- a/include/asm-x86/dma-mapping.h
+++ b/include/asm-x86/dma-mapping.h
@@ -82,4 +82,13 @@
 	BUG_ON(!valid_dma_direction(direction));
 	return dma_ops->map_sg(hwdev, sg, nents, direction);
 }
+
+static inline void
+dma_unmap_sg(struct device *hwdev, struct scatterlist *sg, int nents,
+	     int direction)
+{
+	BUG_ON(!valid_dma_direction(direction));
+	if (dma_ops->unmap_sg)
+		dma_ops->unmap_sg(hwdev, sg, nents, direction);
+}
 #endif
diff --git a/include/asm-x86/dma-mapping_32.h b/include/asm-x86/dma-mapping_32.h
index cdcdeff..55445e3 100644
--- a/include/asm-x86/dma-mapping_32.h
+++ b/include/asm-x86/dma-mapping_32.h
@@ -32,14 +32,6 @@
 	BUG_ON(!valid_dma_direction(direction));
 }
 
-
-static inline void
-dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nhwentries,
-	     enum dma_data_direction direction)
-{
-	BUG_ON(!valid_dma_direction(direction));
-}
-
 static inline void
 dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, size_t size,
 			enum dma_data_direction direction)
diff --git a/include/asm-x86/dma-mapping_64.h b/include/asm-x86/dma-mapping_64.h
index b27527a..ce37efb 100644
--- a/include/asm-x86/dma-mapping_64.h
+++ b/include/asm-x86/dma-mapping_64.h
@@ -96,14 +96,6 @@
 	flush_write_buffers();
 }
 
-static inline void
-dma_unmap_sg(struct device *hwdev, struct scatterlist *sg, int nents,
-	     int direction)
-{
-	BUG_ON(!valid_dma_direction(direction));
-	dma_ops->unmap_sg(hwdev, sg, nents, direction);
-}
-
 extern int dma_supported(struct device *hwdev, u64 mask);
 
 /* same for gart, swiotlb, and nommu */