crypto: shash - fix missed optimization in shash_ahash_digest()

shash_ahash_digest(), which is the ->digest() method for ahash tfms that
use an shash algorithm, has an optimization where crypto_shash_digest()
is called if the data is in a single page.  But an off-by-one error
prevented this path from being taken unless the user happened to provide
extra data in the scatterlist.  Fix it.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/shash.c

@@ -307,7 +307,7 @@ int shash_ahash_digest(struct ahash_request *req, struct shash_desc *desc)
 
 	if (nbytes &&
 	    (sg = req->src, offset = sg->offset,
-	     nbytes < min(sg->length, ((unsigned int)(PAGE_SIZE)) - offset))) {
+	     nbytes <= min(sg->length, ((unsigned int)(PAGE_SIZE)) - offset))) {
 		void *data;
 
 		data = kmap_atomic(sg_page(sg));