x86: make 64bit have get_apic_id

generalize the x2apic code some more.

let read_apic_id become a macro (later on a function/inline)
GET_APIC_ID(apic_read(APIC_ID))

  +#define read_apic_id()  (GET_APIC_ID(apic_read(APIC_ID)))

instead of this weird construct:

  -#define read_apic_id  (genapic->read_apic_id)

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/asm-x86/mach-default/mach_apicdef.h b/include/asm-x86/mach-default/mach_apicdef.h
index 3e1be6c..a55518a 100644
--- a/include/asm-x86/mach-default/mach_apicdef.h
+++ b/include/asm-x86/mach-default/mach_apicdef.h
@@ -4,9 +4,9 @@
 #include <asm/apic.h>
 
 #ifdef CONFIG_X86_64
-#define	APIC_ID_MASK		(0xFFu<<24)
-#define GET_APIC_ID(x)		(((x)>>24) & 0xFFu)
-#define	SET_APIC_ID(x)		(((x)<<24))
+#define	APIC_ID_MASK		(genapic->apic_id_mask)
+#define GET_APIC_ID(x)		(genapic->get_apic_id(x))
+#define	SET_APIC_ID(x)		(genapic->set_apic_id(x))
 #else
 #define		APIC_ID_MASK		(0xF<<24)
 static inline unsigned get_apic_id(unsigned long x)