Kernel: Move all Graphics-related code into Devices/GPU directory

Like the HID, Audio and Storage subsystem, the Graphics subsystem (which
handles GPUs technically) exposes unix device files (typically in /dev).
To ensure consistency across the repository, move all related files to a
new directory under Kernel/Devices called "GPU".

Also remove the redundant "GPU" word from the VirtIO driver directory,
and the word "Graphics" from GraphicsManagement.{h,cpp} filenames.

Kernel/Devices/GPU/Intel/Definitions.h

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+
+namespace Kernel::IntelGraphics {
+
+enum class Generation {
+    Gen4,
+    Gen9,
+};
+
+struct PLLSettings;
+
+struct PLLParameterLimit {
+    size_t min, max;
+};
+
+struct PLLMaxSettings {
+    PLLParameterLimit dot_clock, vco, n, m, m1, m2, p, p1, p2;
+};
+
+struct PLLSettings {
+    bool is_valid() const { return (n != 0 && m1 != 0 && m2 != 0 && p1 != 0 && p2 != 0); }
+    u64 compute_dot_clock(u64 refclock) const
+    {
+        return (refclock * (5 * m1 + m2) / n) / (p1 * p2);
+    }
+
+    u64 compute_vco(u64 refclock) const
+    {
+        return refclock * (5 * m1 + m2) / n;
+    }
+
+    u64 compute_m() const
+    {
+        return 5 * m1 + m2;
+    }
+
+    u64 compute_p() const
+    {
+        return p1 * p2;
+    }
+    u64 n { 0 };
+    u64 m1 { 0 };
+    u64 m2 { 0 };
+    u64 p1 { 0 };
+    u64 p2 { 0 };
+};
+}