system: fix loading of crypto/thermal modules

PR: https://forum.opnsense.org/index.php?topic=4094

src/etc/inc/system.inc

@@ -1483,6 +1483,8 @@ function get_possible_listen_ips($include_ipv6_link_local = false, $include_loop
 
 function system_kernel_configure($verbose = false)
 {
+    global $config;
+
     if ($verbose) {
         echo 'Configuring kernel modules...';
         flush();