system: fix loading of crypto/thermal modules

PR: https://forum.opnsense.org/index.php?topic=4094
(cherry picked from commit 26d9815d)

src/etc/inc/system.inc

@@ -1452,6 +1452,8 @@ 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();