tile: fix a -Wframe-larger-than warning

The warning occurs in setup.c, where it is known that it can't be
a problem, but it's still a good idea to silence the warning.
The onstack array is converted from an s32 to a u8, which still
is plenty of range for the values being managed there.
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>

arch/tile/kernel/setup.c

@@ -882,7 +882,7 @@ static int __init node_neighbors(int node, int cpu,
 
 static void __init setup_numa_mapping(void)
 {
-	int distance[MAX_NUMNODES][NR_CPUS];
+	u8 distance[MAX_NUMNODES][NR_CPUS];
 	HV_Coord coord;
 	int cpu, node, cpus, i, x, y;
 	int num_nodes = num_online_nodes();