powerpc/numa: Suppress "VPHN is not supported" messages

When VPHN function is not supported and during cpu hotplug event,
kernel prints message 'VPHN function not supported. Disabling
polling...'. Currently it prints on every hotplug event, it floods
dmesg when a KVM guest tries to hotplug huge number of vcpus, let's
just print once and suppress further kernel prints.
Signed-off-by: NSatheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/numa.c

@@ -1178,7 +1178,7 @@ static long vphn_get_associativity(unsigned long cpu,
 
 	switch (rc) {
 	case H_FUNCTION:
-		printk(KERN_INFO
+		printk_once(KERN_INFO
 			"VPHN is not supported. Disabling polling...\n");
 		stop_topology_update();
 		break;