vnc-auth-sasl: Plug memleak in vnc_socket_ip_addr_string

'addr' is forgot to free in vnc_socket_ip_addr_string error path. Fix that.

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Message-Id: <20200831134315.1221-11-pannengyuan@huawei.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

ui/vnc-auth-sasl.c

@@ -522,6 +522,7 @@ vnc_socket_ip_addr_string(QIOChannelSocket *ioc,
 
     if (addr->type != SOCKET_ADDRESS_TYPE_INET) {
         error_setg(errp, "Not an inet socket type");
+        qapi_free_SocketAddress(addr);
         return NULL;
     }
     ret = g_strdup_printf("%s;%s", addr->u.inet.host, addr->u.inet.port);