s390: typo fix

s390 code has an obvious typo, which results in:
hw/s390-virtio.c: At top level:
hw/s390-virtio.c:249: error: request for member ‘no_vga’ in something not a structure or union
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

hw/s390-virtio.c

@@ -245,7 +245,7 @@ static QEMUMachine s390_machine = {
     .init = s390_init,
     .no_serial = 1,
     .no_parallel = 1,
-    .use_virtcon = 1.
+    .use_virtcon = 1,
     .no_vga = 1,
     .max_cpus = 255,
     .is_default = 1,