x86: move dma_map_page and dma_unmap_page to common header

They are similar enough to do this move.
the macro version is ugly, and we use inline functions instead.

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 3ea3802..b5a413a 100644
--- a/include/asm-x86/dma-mapping.h
+++ b/include/asm-x86/dma-mapping.h
@@ -169,4 +169,18 @@
 
 	flush_write_buffers();
 }
+
+static inline dma_addr_t dma_map_page(struct device *dev, struct page *page,
+				      size_t offset, size_t size,
+				      int direction)
+{
+	return dma_map_single(dev, page_address(page)+offset, size, direction);
+}
+
+static inline void dma_unmap_page(struct device *dev, dma_addr_t addr,
+				  size_t size, int direction)
+{
+	dma_unmap_single(dev, addr, size, direction);
+}
+
 #endif