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

pcibus_to_node can return -1 if we cannot determine which node a pci bus
is on. If passed -1, cpumask_of_node will negatively index the lookup array
and pull in random data:

# cat /sys/devices/pci0000:00/0000:00:01.0/local_cpus
00000000,00000003,00000000,00000000
# cat /sys/devices/pci0000:00/0000:00:01.0/local_cpulist
64-65

Change cpumask_of_node to check for -1 and return cpu_all_mask in this
case:

# cat /sys/devices/pci0000:00/0000:00:01.0/local_cpus
ffffffff,ffffffff,ffffffff,ffffffff
# cat /sys/devices/pci0000:00/0000:00:01.0/local_cpulist
0-127
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/topology.h

@@ -17,7 +17,9 @@ static inline int cpu_to_node(int cpu)
 
 #define parent_node(node)	(node)
 
-#define cpumask_of_node(node) (&numa_cpumask_lookup_table[node])
+#define cpumask_of_node(node) ((node) == -1 ?				\
+			       cpu_all_mask :				\
+			       &numa_cpumask_lookup_table[node])
 
 int of_node_to_nid(struct device_node *device);