Kernel: Unbreak /proc/interrupts when running with APIC

We can't assert here since these are exposed through /proc JSON.

Kernel/Interrupts/APIC.cpp

@@ -92,7 +92,7 @@ public:
 
     virtual HandlerType type() const override { return HandlerType::IRQHandler; }
     virtual const char* purpose() const override { return "IPI Handler"; }
-    virtual const char* controller() const override { ASSERT_NOT_REACHED(); }
+    virtual const char* controller() const override { return nullptr; }
 
     virtual size_t sharing_devices_count() const override { return 0; }
     virtual bool is_shared_handler() const override { return false; }
@@ -122,7 +122,7 @@ public:
 
     virtual HandlerType type() const override { return HandlerType::IRQHandler; }
     virtual const char* purpose() const override { return "SMP Error Handler"; }
-    virtual const char* controller() const override { ASSERT_NOT_REACHED(); }
+    virtual const char* controller() const override { return nullptr; }
 
     virtual size_t sharing_devices_count() const override { return 0; }
     virtual bool is_shared_handler() const override { return false; }