x86: introduce gate_desc type.

To account for the differences in gate descriptor in i386 and x86_64
a gate_desc type is introduced.

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/traps_32.c

@@ -76,7 +76,7 @@ char ignore_fpu_irq = 0;
  * F0 0F bug workaround.. We have a special link segment
  * for this.
  */
-struct desc_struct idt_table[256]
+gate_desc idt_table[256]
 	__attribute__((__section__(".data.idt"))) = { { { { 0, 0 } } }, };
 
 asmlinkage void divide_error(void);