alpha: cpumask_of_node() should handle -1 as a node

CC: Richard Henderson <rth@twiddle.net>
CC: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: NMatt Turner <mattst88@gmail.com>
CC: linux-alpha@vger.kernel.org
CC: Rusty Russell <rusty@rustcorp.com.au>
CC: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAnton Blanchard <anton@samba.org>

arch/alpha/include/asm/topology.h

@@ -28,6 +28,9 @@ static const struct cpumask *cpumask_of_node(int node)
 {
 	int cpu;
 
+	if (node == -1)
+		return cpu_all_mask;
+
 	cpumask_clear(&node_to_cpumask_map[node]);
 
 	for_each_online_cpu(cpu) {