crypto: replace scatterwalk_sg_next with sg_next

Modify crypto drivers to use the generic SG helper since
both of them are equivalent and the one from crypto is redundant.

See also:
  468577abe37ff7b453a9ac613e0ea155349203ae   reverted in
  b2ab4a57b018aafbba35bff088218f5cc3d2142e

Signed-off-by: Cristian Stoica <cristian.stoica@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/drivers/crypto/nx/nx.c b/drivers/crypto/nx/nx.c
index a392465..1da6dc5 100644
--- a/drivers/crypto/nx/nx.c
+++ b/drivers/crypto/nx/nx.c
@@ -177,7 +177,7 @@
 			break;
 
 		offset += sg_src->length;
-		sg_src = scatterwalk_sg_next(sg_src);
+		sg_src = sg_next(sg_src);
 	}
 
 	/* start - offset is the number of bytes to advance in the scatterlist
@@ -187,9 +187,9 @@
 	while (len && (nx_sg - nx_dst) < sglen) {
 		n = scatterwalk_clamp(&walk, len);
 		if (!n) {
-			/* In cases where we have scatterlist chain scatterwalk_sg_next
+			/* In cases where we have scatterlist chain sg_next
 			 * handles with it properly */
-			scatterwalk_start(&walk, scatterwalk_sg_next(walk.sg));
+			scatterwalk_start(&walk, sg_next(walk.sg));
 			n = scatterwalk_clamp(&walk, len);
 		}
 		dst = scatterwalk_map(&walk);