msm: timer: fix missing return value

Change af90f10d "ARM: 6759/1: smp: Select local timers vs broadcast
timer support runtime" missed a return statement, causing a compile
warning:

  arch/arm/mach-msm/timer.c:272: warning: 'return' with no value, in
  function returning non-void

Trivially return 0 for success when running on cpu 0 (to match the
comment and previous behavior).
Signed-off-by: David Brown <davidb@codeaurora.org>

arch/arm/mach-msm/timer.c

@@ -269,7 +269,7 @@ int __cpuinit local_timer_setup(struct clock_event_device *evt)
 
 	/* Use existing clock_event for cpu 0 */
 	if (!smp_processor_id())
-		return;
+		return 0;
 
 	writel(DGT_CLK_CTL_DIV_4, MSM_TMR_BASE + DGT_CLK_CTL);