x86: smp.h remove obsolete function declaration

Impact: cleanup
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/include/asm/smp.h

@@ -22,7 +22,6 @@ extern cpumask_t cpu_callout_map;
 extern cpumask_t cpu_initialized;
 extern cpumask_t cpu_callin_map;
 
-extern void (*mtrr_hook)(void);
 extern void zap_low_mappings(void);
 
 extern int __cpuinit get_local_pda(int cpu);