ARM: localtimer: clean up local timer on hot unplug

When a CPU is hot unplugged, the generic tick code cleans up the
clock event device, but fails to call down to the device's set_mode
function to actually shut the device down.

To work around this, we've historically had a local_timer_stop()
callback out of the hotplug code.  However, this adds needless
complexity when we have the clock event device itself available.

Explicitly call the clock event device's set_mode function with
CLOCK_EVT_MODE_UNUSED, so that the hardware can be cleanly shutdown
without any special external callbacks.  When/if the generic code
is fixed, percpu_timer_stop() can be killed off.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/localtimer.h

@@ -30,7 +30,6 @@ asmlinkage void do_local_timer(struct pt_regs *);
 #include "smp_twd.h"
 
 #define local_timer_ack()	twd_timer_ack()
-#define local_timer_stop()	twd_timer_stop()
 
 #else
 
@@ -40,11 +39,6 @@ asmlinkage void do_local_timer(struct pt_regs *);
  */
 int local_timer_ack(void);
 
-/*
- * Stop a local timer interrupt.
- */
-void local_timer_stop(void);
-
 #endif
 
 /*
@@ -52,12 +46,6 @@ void local_timer_stop(void);
  */
 void local_timer_setup(struct clock_event_device *);
 
-#else
-
-static inline void local_timer_stop(void)
-{
-}
-
 #endif
 
 #endif