vl.c: Use MAX_CPUMASK_BITS macro instead of hardcoded constant

Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

vl.c

@@ -1413,7 +1413,7 @@ static void smp_parse(QemuOpts *opts)
         max_cpus = smp_cpus;
     }
 
-    if (max_cpus > 255) {
+    if (max_cpus > MAX_CPUMASK_BITS) {
         fprintf(stderr, "Unsupported number of maxcpus\n");
         exit(1);
     }