ssb: remove unreachable code

The return value of ssb_bus_unregister can only be 0 or -1, so this
condition if (err == -EBUSY) will not hold, so delete it.

Signed-off-by: Tian Tao <[e-mail]>
Acked-by: Michael Büsch <[e-mail]>
Signed-off-by: Kalle Valo <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/ssb/main.c

···
 	int err;
 
 	err = ssb_gpio_unregister(bus);
-	if (err == -EBUSY)
-		pr_debug("Some GPIOs are still in use\n");
-	else if (err)
+	if (err)
 		pr_debug("Can not unregister GPIO driver: %i\n", err);
 
 	ssb_buses_lock();