crypto: arm/ghash - use the new scatterwalk functions

Use scatterwalk_next() which consolidates scatterwalk_clamp() and
scatterwalk_map(), and use scatterwalk_done_src() which consolidates
scatterwalk_unmap(), scatterwalk_advance(), and scatterwalk_done().
Remove unnecessary code that seemed to be intended to advance to the
next sg entry, which is already handled by the scatterwalk functions.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Author: ebiggers

arch/arm/crypto/ghash-ce-glue.c

@@ -459,26 +459,19 @@ static void gcm_calculate_auth_mac(struct aead_request *req, u64 dg[], u32 len)
 	scatterwalk_start(&walk, req->src);
 
 	do {
-		u32 n = scatterwalk_clamp(&walk, len);
-		u8 *p;
+		unsigned int n;
+		const u8 *p;
 
-		if (!n) {
-			scatterwalk_start(&walk, sg_next(walk.sg));
-			n = scatterwalk_clamp(&walk, len);
-		}
-
-		p = scatterwalk_map(&walk);
+		p = scatterwalk_next(&walk, len, &n);
 		gcm_update_mac(dg, p, n, buf, &buf_count, ctx);
-		scatterwalk_unmap(p);
+		scatterwalk_done_src(&walk, p, n);
 
 		if (unlikely(len / SZ_4K > (len - n) / SZ_4K)) {
 			kernel_neon_end();
 			kernel_neon_begin();
 		}
 
 		len -= n;
-		scatterwalk_advance(&walk, n);
-		scatterwalk_done(&walk, 0, len);
 	} while (len);
 
 	if (buf_count) {