Kernel/IntelGraphics: Move PLL handling code to a different file

Dealing with the specific details of how to program a PLL should be done
in a separate file to ensure we can easily expand it to support future
generations of the Intel graphics device.

Kernel/Graphics/Intel/Transcoder/PLL.h

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2023, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Optional.h>
+#include <Kernel/Graphics/Intel/Definitions.h>
+
+namespace Kernel::IntelGraphics {
+
+PLLMaxSettings const& pll_max_settings_for_generation(Generation);
+Optional<PLLSettings> create_pll_settings(Generation, u64 target_frequency, u64 reference_clock);
+bool check_pll_settings(PLLSettings const& settings, size_t reference_clock, PLLMaxSettings const& limits);
+
+}