ia64: move function declaration, ia64_cpu_local_tick() from .c to .h

eliminate the function declaration ia64_cpu_local_tick() in
process.c by defining in arch/ia64/include/asm/timex.h
The same function will be used in a different .c file later.
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/include/asm/timex.h

@@ -39,4 +39,6 @@ get_cycles (void)
 	return ret;
 }
 
+extern void ia64_cpu_local_tick (void);
+
 #endif /* _ASM_IA64_TIMEX_H */

arch/ia64/kernel/process.c

@@ -251,7 +251,6 @@ default_idle (void)
 /* We don't actually take CPU down, just spin without interrupts. */
 static inline void play_dead(void)
 {
-	extern void ia64_cpu_local_tick (void);
 	unsigned int this_cpu = smp_processor_id();
 
 	/* Ack it */