x86: add safe_smp_processor_id for x86_64

Preperatory patch to allow crash_32/64.c merging
Signed-off-by: NHiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

include/asm-x86/smp_64.h

@@ -76,6 +76,8 @@ extern unsigned __cpuinitdata disabled_cpus;
 
 #endif /* CONFIG_SMP */
 
+#define safe_smp_processor_id()		smp_processor_id()
+
 static inline int hard_smp_processor_id(void)
 {
 	/* we don't want to mark this access volatile - bad code generation */