thunderbolt: Check for unplugged router in tb_switch_clx_disable()

There is no point disabling CL states if the router is unplugged so in
that case return early.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/clx.c

@@ -405,6 +405,9 @@ int tb_switch_clx_disable(struct tb_switch *sw)
 	if (!clx)
 		return 0;
 
+	if (sw->is_unplugged)
+		return clx;
+
 	up = tb_upstream_port(sw);
 	down = tb_switch_downstream_port(sw);