remove unused lock_cpu_hotplug_interruptible definition

aa953877 removed the implementation of
lock_cpu_hotplug_interruptible and all users of it.  This stub definition
for !CONFIG_HOTPLUG_CPU was left over -- kill it now.
Signed-off-by: Nathan Lynch <ntl@pobox.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/cpu.h

@@ -120,7 +120,6 @@ static inline void cpuhotplug_mutex_unlock(struct mutex *cpu_hp_mutex)
 
 #define lock_cpu_hotplug()	do { } while (0)
 #define unlock_cpu_hotplug()	do { } while (0)
-#define lock_cpu_hotplug_interruptible() 0
 #define hotcpu_notifier(fn, pri)	do { (void)(fn); } while (0)
 #define register_hotcpu_notifier(nb)	do { (void)(nb); } while (0)
 #define unregister_hotcpu_notifier(nb)	do { (void)(nb); } while (0)