x86: Move the GDT into global_data

Rather than keeping track of the Global Descriptor Table in its own memory
we may as well put it in global_data with everything else. As a first step,
stop using the separately allocated GDT.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/cpu/cpu.c b/arch/x86/cpu/cpu.c
index 129777c..4f57145 100644
--- a/arch/x86/cpu/cpu.c
+++ b/arch/x86/cpu/cpu.c
@@ -136,9 +136,10 @@
 	asm volatile("lgdtl %0\n" : : "m" (gdt));
 }
 
-void setup_gdt(gd_t *id, u64 *gdt_addr)
+void setup_gdt(gd_t *new_gd, u64 *gdt_addr)
 {
-	id->arch.gdt = gdt_addr;
+	gdt_addr = new_gd->arch.gdt;
+
 	/* CS: code, read/execute, 4 GB, base 0 */
 	gdt_addr[X86_GDT_ENTRY_32BIT_CS] = GDT_ENTRY(0xc09b, 0, 0xfffff);
 
@@ -146,9 +147,9 @@
 	gdt_addr[X86_GDT_ENTRY_32BIT_DS] = GDT_ENTRY(0xc093, 0, 0xfffff);
 
 	/* FS: data, read/write, 4 GB, base (Global Data Pointer) */
-	id->arch.gd_addr = id;
+	new_gd->arch.gd_addr = new_gd;
 	gdt_addr[X86_GDT_ENTRY_32BIT_FS] = GDT_ENTRY(0xc093,
-		     (ulong)&id->arch.gd_addr, 0xfffff);
+		     (ulong)&new_gd->arch.gd_addr, 0xfffff);
 
 	/* 16-bit CS: code, read/execute, 64 kB, base 0 */
 	gdt_addr[X86_GDT_ENTRY_16BIT_CS] = GDT_ENTRY(0x009b, 0, 0x0ffff);