ARM: spear: send SGI to trigger secondary CPU start

The ARM spear machine uses the "holding pen" mechanism for starting secondary CPUs. Most implementations indicate it's a secondary core's time to start by writing its CPU id into a location and then signaling the core with a software-generated interrupt.

The spear code does not send the signal. Comments elsewhere in the code seem to indicate it should:
The BootMonitor waits until it receives a soft interrupt, and then the secondary CPU branches to this address.

I suspect this is an oversight, and this patch proposes a remedy.

*** I need the attention of a maintainer to verify this *** because I am unable to test this proposed change.

---
 arch/arm/mach-spear/platsmp.c |    2 ++
 1 file changed, 2 insertions(+)

index 5c4a198..c9064fe 100644
@@ -62,6 +62,8 @@ static int spear13xx_boot_secondary(unsigned int cpu, struct task_struct *idle)
 	flush_cache_all();
 	outer_flush_all();
 
+	arch_send_wakeup_ipi_mask(cpumask_of(cpu));
+
 	timeout = jiffies + (1 * HZ);
 	while (time_before(jiffies, timeout)) {
 		smp_rmb();

1.7.9.5