POWERPC: Smp: remove call to ipi_call_lock()/ipi_call_unlock()

ipi_call_lock/unlock() lock resp. unlock call_function.lock. This lock
protects only the call_function data structure itself, but it's
completely unrelated to cpu_online_mask. The mask to which the IPIs
are sent is calculated before call_function.lock is taken in
smp_call_function_many(), so the locking around set_cpu_online() is
pointless and can be removed.

[ tglx: Massaged changelog ]

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: ralf@linux-mips.org
Cc: sshtylyov@mvista.com
Cc: david.daney@cavium.com
Cc: nikunj@linux.vnet.ibm.com
Cc: paulmck@linux.vnet.ibm.com
Cc: axboe@kernel.dk
Cc: peterz@infradead.org
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1338275765-3217-10-git-send-email-yong.zhang0@gmail.com
Acked-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/powerpc/kernel/smp.c

@@ -571,7 +571,6 @@ void __devinit start_secondary(void *unused)
 	if (system_state == SYSTEM_RUNNING)
 		vdso_data->processorCount++;
 #endif
-	ipi_call_lock();
 	notify_cpu_starting(cpu);
 	set_cpu_online(cpu, true);
 	/* Update sibling maps */
@@ -601,7 +600,6 @@ void __devinit start_secondary(void *unused)
 		of_node_put(np);
 	}
 	of_node_put(l2_cache);
-	ipi_call_unlock();
 
 	local_irq_enable();