sock: Fix SO_ZEROCOPY switch case

Fix the SO_ZEROCOPY switch case on sock_setsockopt() avoiding the
ret values to be overwritten by the one set on the default case.

Fixes: 28190752c7 ("sock: permit SO_ZEROCOPY on PF_RDS socket")
Signed-off-by: Jesus Sanchez-Palencia <jesus.sanchez-palencia@intel.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Acked-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/sock.c

@@ -1062,8 +1062,9 @@ set_rcvbuf:
 				ret = -EINVAL;
 			else
 				sock_valbool_flag(sk, SOCK_ZEROCOPY, valbool);
-			break;
 		}
+		break;
+
 	default:
 		ret = -ENOPROTOOPT;
 		break;