Remove parentheses of return.

Since return is inconsistent, I removed unnecessary parentheses and
unified them.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4541)

ssl/statem/statem_clnt.c

diff --git a/ssl/statem/statem_clnt.c b/ssl/statem/statem_clnt.c
index 338325f..af42bcb 100644
--- a/ssl/statem/statem_clnt.c
+++ b/ssl/statem/statem_clnt.c
@@ -3474,7 +3474,7 @@
     ssl_set_client_disabled(s);
 
     if (sk == NULL)
-        return (0);
+        return 0;
 
 #ifdef OPENSSL_MAX_TLS1_2_CIPHER_LENGTH
 # if OPENSSL_MAX_TLS1_2_CIPHER_LENGTH < 6