Revert "Kernel: Switch singletons to use new Singleton class"

This reverts commit f48feae0b2.

Kernel/Random.cpp

@@ -28,15 +28,17 @@
 #include <Kernel/Arch/i386/CPU.h>
 #include <Kernel/Devices/RandomDevice.h>
 #include <Kernel/Random.h>
-#include <Kernel/Singleton.h>
 #include <Kernel/Time/TimeManagement.h>
 
 namespace Kernel {
 
-static auto s_the = make_singleton<KernelRng>();
+static KernelRng* s_the;
 
 KernelRng& KernelRng::the()
 {
+    if (!s_the) {
+        s_the = new KernelRng;
+    }
     return *s_the;
 }