crypto: don't pollute the global namespace with sg_next()

It's a subsystem function, prefix it as such.
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

crypto/digest.c

@@ -77,7 +77,7 @@ static int update2(struct hash_desc *desc,
 
 		if (!nbytes)
 			break;
-		sg = sg_next(sg);
+		sg = scatterwalk_sg_next(sg);
 	}
 
 	return 0;

crypto/scatterwalk.c

@@ -62,7 +62,7 @@ static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
 		walk->offset += PAGE_SIZE - 1;
 		walk->offset &= PAGE_MASK;
 		if (walk->offset >= walk->sg->offset + walk->sg->length)
-			scatterwalk_start(walk, sg_next(walk->sg));
+			scatterwalk_start(walk, scatterwalk_sg_next(walk->sg));
 	}
 }
 

crypto/scatterwalk.h

@@ -20,7 +20,7 @@
 
 #include "internal.h"
 
-static inline struct scatterlist *sg_next(struct scatterlist *sg)
+static inline struct scatterlist *scatterwalk_sg_next(struct scatterlist *sg)
 {
 	return (++sg)->length ? sg : (void *)sg->page;
 }