powerpc/iommu: Rename iommu_[un]map_sg functions

The IOMMU-API gained support for a new iommu_map_sg
function. This causes compile failures on powerpc because
the function name is already globally used there.
This patch renames adds a ppc_ prefix to these functions to
solve the compile problem.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index 42632c7..9cfa370 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -137,13 +137,16 @@
 	iommu_add_device(dev);
 }
 
-extern int iommu_map_sg(struct device *dev, struct iommu_table *tbl,
-			struct scatterlist *sglist, int nelems,
-			unsigned long mask, enum dma_data_direction direction,
-			struct dma_attrs *attrs);
-extern void iommu_unmap_sg(struct iommu_table *tbl, struct scatterlist *sglist,
-			   int nelems, enum dma_data_direction direction,
-			   struct dma_attrs *attrs);
+extern int ppc_iommu_map_sg(struct device *dev, struct iommu_table *tbl,
+			    struct scatterlist *sglist, int nelems,
+			    unsigned long mask,
+			    enum dma_data_direction direction,
+			    struct dma_attrs *attrs);
+extern void ppc_iommu_unmap_sg(struct iommu_table *tbl,
+			       struct scatterlist *sglist,
+			       int nelems,
+			       enum dma_data_direction direction,
+			       struct dma_attrs *attrs);
 
 extern void *iommu_alloc_coherent(struct device *dev, struct iommu_table *tbl,
 				  size_t size, dma_addr_t *dma_handle,