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/include/crypto/scatterwalk.h b/include/crypto/scatterwalk.h
index 7ef512f..20e4226 100644
--- a/include/crypto/scatterwalk.h
+++ b/include/crypto/scatterwalk.h
@@ -33,21 +33,13 @@
 	sg1[num - 1].page_link |= 0x01;
 }
 
-static inline struct scatterlist *scatterwalk_sg_next(struct scatterlist *sg)
-{
-	if (sg_is_last(sg))
-		return NULL;
-
-	return (++sg)->length ? sg : sg_chain_ptr(sg);
-}
-
 static inline void scatterwalk_crypto_chain(struct scatterlist *head,
 					    struct scatterlist *sg,
 					    int chain, int num)
 {
 	if (chain) {
 		head->length += sg->length;
-		sg = scatterwalk_sg_next(sg);
+		sg = sg_next(sg);
 	}
 
 	if (sg)