powerpc: Drop return value of smp_ops->probe()

smp_ops->probe() is currently supposed to return the number of cpus in
the system.

The last actual usage of the value was removed in May 2007 in e147ec8f18
"[POWERPC] Simplify smp_space_timers". We still passed the value around
until June 2010 when even that was finally removed in c1aa687d49
"powerpc: Clean up obsolete code relating to decrementer and timebase".

So drop that requirement, probe() now returns void, and update all
implementations.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/sysdev/xics/xics-common.c

@@ -140,15 +140,13 @@ static void xics_request_ipi(void)
 			   IRQF_PERCPU | IRQF_NO_THREAD, "IPI", NULL));
 }
 
-int __init xics_smp_probe(void)
+void __init xics_smp_probe(void)
 {
 	/* Setup cause_ipi callback  based on which ICP is used */
 	smp_ops->cause_ipi = icp_ops->cause_ipi;
 
 	/* Register all the IPIs */
 	xics_request_ipi();
-
-	return num_possible_cpus();
 }
 
 #endif /* CONFIG_SMP */