sparc: use for_each_sg()

This replaces the plain loop over the sglist array with for_each_sg()
macro which consists of sg_next() function calls.  Since sparc does select
ARCH_HAS_SG_CHAIN, it is necessary to use for_each_sg() in order to loop
over each sg element.  This also help find problems with drivers that do
not properly initialize their sg tables when CONFIG_DEBUG_SG is enabled.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/sparc/kernel/ldc.c

@@ -2086,6 +2086,7 @@ int ldc_map_sg(struct ldc_channel *lp,
 	struct cookie_state state;
 	struct ldc_iommu *iommu;
 	int err;
+	struct scatterlist *s;
 
 	if (map_perm & ~LDC_MAP_ALL)
 		return -EINVAL;
@@ -2112,9 +2113,10 @@ int ldc_map_sg(struct ldc_channel *lp,
 	state.pte_idx = (base - iommu->page_table);
 	state.nc = 0;
 
-	for (i = 0; i < num_sg; i++)
-		fill_cookies(&state, page_to_pfn(sg_page(&sg[i])) << PAGE_SHIFT,
-			     sg[i].offset, sg[i].length);
+	for_each_sg(sg, s, num_sg, i) {
+		fill_cookies(&state, page_to_pfn(sg_page(s)) << PAGE_SHIFT,
+			     s->offset, s->length);
+	}
 
 	return state.nc;
 }