Kernel: Use a const reference to RegisterState in IRQ handling

Author: https://github.com/supercomputer7
Commit: e880fe0765
Pull-request: https://github.com/SerenityOS/serenity/pull/1396
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/shannonbooth ✅

Kernel/Devices/PS2MouseDevice.h

@@ -52,7 +52,7 @@ public:
 private:
     // ^IRQHandler
     void handle_vmmouse_absolute_pointer();
-    virtual void handle_irq(RegisterState&) override;
+    virtual void handle_irq(const RegisterState&) override;
 
     // ^CharacterDevice
     virtual const char* class_name() const override { return "PS2MouseDevice"; }