Kernel: Reorganize Arch/x86 directory to Arch/x86_64 after i686 removal

No functional change.

Kernel/Arch/x86_64/TSS.h

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Leon Albrecht <leon2002.la@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+
+#include <AK/Platform.h>
+VALIDATE_IS_X86()
+
+namespace Kernel {
+
+struct [[gnu::packed]] TSS32 {
+    u16 backlink, __blh;
+    u32 esp0;
+    u16 ss0, __ss0h;
+    u32 esp1;
+    u16 ss1, __ss1h;
+    u32 esp2;
+    u16 ss2, __ss2h;
+    u32 cr3, eip, eflags;
+    u32 eax, ecx, edx, ebx, esp, ebp, esi, edi;
+    u16 es, __esh;
+    u16 cs, __csh;
+    u16 ss, __ssh;
+    u16 ds, __dsh;
+    u16 fs, __fsh;
+    u16 gs, __gsh;
+    u16 ldt, __ldth;
+    u16 trace, iomapbase;
+};
+
+struct [[gnu::packed]] TSS64 {
+    u32 __1; // Link?
+    u32 rsp0l;
+    u32 rsp0h;
+    u32 rsp1l;
+    u32 rsp1h;
+    u32 rsp2l;
+    u32 rsp2h;
+    u64 __2; // probably CR3 and EIP?
+    u32 ist1l;
+    u32 ist1h;
+    u32 ist2l;
+    u32 ist2h;
+    u32 ist3l;
+    u32 ist3h;
+    u32 ist4l;
+    u32 ist4h;
+    u32 ist5l;
+    u32 ist5h;
+    u32 ist6l;
+    u32 ist6h;
+    u32 ist7l;
+    u32 ist7h;
+    u64 __3; // GS and LDTR?
+    u16 __4;
+    u16 iomapbase;
+};
+
+using TSS = TSS64;
+
+}