crypto: aead - fixed style error in aead.c

Fixed style error identified by checkpatch.

ERROR: do not use assignment in if condition
+       if ((err = crypto_register_instance(tmpl, inst))) {
Signed-off-by: Joshua I. James <joshua@cybercrimetech.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/aead.c

@@ -448,7 +448,8 @@ static int crypto_nivaead_default(struct crypto_alg *alg, u32 type, u32 mask)
 	if (IS_ERR(inst))
 		goto put_tmpl;
 
-	if ((err = crypto_register_instance(tmpl, inst))) {
+	err = crypto_register_instance(tmpl, inst);
+	if (err) {
 		tmpl->free(inst);
 		goto put_tmpl;
 	}