x86: provide tss_desc

Provide a new type, tss_desc, to represent the tss descriptor
in a unified way accross x86_64 and i386

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>

include/asm-x86/desc_defs.h

@@ -70,9 +70,11 @@ struct ldttss_desc64 {
 #ifdef CONFIG_X86_64
 typedef struct gate_struct64 gate_desc;
 typedef struct ldttss_desc64 ldt_desc;
+typedef struct ldttss_desc64 tss_desc;
 #else
 typedef struct desc_struct gate_desc;
 typedef struct desc_struct ldt_desc;
+typedef struct desc_struct tss_desc;
 #endif
 
 struct desc_ptr {