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 e147ec8f1808
"[POWERPC] Simplify smp_space_timers". We still passed the value around
until June 2010 when even that was finally removed in c1aa687d499a
"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>
diff --git a/arch/powerpc/platforms/ps3/smp.c b/arch/powerpc/platforms/ps3/smp.c
index b358bec..3c7707a 100644
--- a/arch/powerpc/platforms/ps3/smp.c
+++ b/arch/powerpc/platforms/ps3/smp.c
@@ -57,7 +57,7 @@
 			" (%d)\n", __func__, __LINE__, cpu, msg, result);
 }
 
-static int __init ps3_smp_probe(void)
+static void __init ps3_smp_probe(void)
 {
 	int cpu;
 
@@ -100,8 +100,6 @@
 
 		DBG(" <- %s:%d: (%d)\n", __func__, __LINE__, cpu);
 	}
-
-	return 2;
 }
 
 void ps3_smp_cleanup_cpu(int cpu)