Kernel/Graphics: Move x86-specific support for VGA to Arch/x86 directory

The new VGAIOArbiter class is now responsible to conduct x86-specific
instructions to control VGA hardware from the old ISA ports. This allows
us to ensure the GraphicsManagement code doesn't use x86-specific code,
thus allowing it to be compiled within non-x86 kernel builds.

Kernel/Graphics/GraphicsManagement.h

@@ -7,7 +7,11 @@
 #pragma once
 
 #include <AK/NonnullOwnPtr.h>
+#include <AK/Platform.h>
 #include <AK/Types.h>
+#if ARCH(I386) || ARCH(X86_64)
+#    include <Kernel/Arch/x86/VGA/IOArbiter.h>
+#endif
 #include <Kernel/Bus/PCI/Definitions.h>
 #include <Kernel/Graphics/Console/Console.h>
 #include <Kernel/Graphics/DisplayConnector.h>
@@ -61,9 +65,9 @@ private:
     unsigned m_current_minor_number { 0 };
 
     SpinlockProtected<IntrusiveList<&DisplayConnector::m_list_node>> m_display_connector_nodes { LockRank::None };
-
-    RecursiveSpinlock m_main_vga_lock { LockRank::None };
-    bool m_vga_access_is_disabled { false };
+#if ARCH(I386) || ARCH(X86_64)
+    OwnPtr<VGAIOArbiter> m_vga_arbiter;
+#endif
 };
 
 }