Kernel/Interrupts: Remove stale MSIHandler class

When we implement MSI support, we can rely on the IRQHandler class for
installing IRQ handlers at the right location.

Kernel/Interrupts/MSIHandler.h

@@ -1,38 +0,0 @@
-/*
- * Copyright (c) 2020, Liav A. <liavalb@hotmail.co.il>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-#pragma once
-
-#include <AK/Types.h>
-#include <Kernel/Interrupts/GenericInterruptHandler.h>
-#include <Kernel/PCI/Definitions.h>
-
-namespace Kernel {
-
-class MSIHandler final : public GenericInterruptHandler {
-public:
-    virtual ~MSIHandler();
-
-    virtual void handle_interrupt(RegisterState&) override { }
-
-    void enable_irq();
-    void disable_irq();
-
-    virtual bool eoi() override;
-
-    virtual size_t sharing_devices_count() const override { return 0; }
-    virtual bool is_shared_handler() const override { return false; }
-    virtual bool is_sharing_with_others() const override { return m_shared_with_others; }
-
-protected:
-    void change_irq_number(u8 irq);
-    explicit MSIHandler(PCI::Address);
-
-private:
-    bool m_shared_with_others;
-    bool m_enabled;
-};
-}