crypto: use ERR_CAST

Replace PTR_ERR followed by ERR_PTR by ERR_CAST, to be more concise.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression err,x;
@@
-       err = PTR_ERR(x);
        if (IS_ERR(x))
-                return ERR_PTR(err);
+                return ERR_CAST(x);
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/authenc.c

@@ -592,9 +592,8 @@ static struct crypto_instance *crypto_authenc_alloc(struct rtattr **tb)
 	int err;
 
 	algt = crypto_get_attr_type(tb);
-	err = PTR_ERR(algt);
 	if (IS_ERR(algt))
-		return ERR_PTR(err);
+		return ERR_CAST(algt);
 
 	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 		return ERR_PTR(-EINVAL);