pcmcia: make pcmcia_release_io() void, as no-one is interested in return value

As the only user of pcmcia_release_io() is not interested in its return
value, and we cannot do anything on failure, convert the function to return
void.
Reported-by: Jason Wang <wangborong@cdjrlc.com>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

drivers/pcmcia/pcmcia_resource.c

@@ -390,10 +390,9 @@ int pcmcia_release_configuration(struct pcmcia_device *p_dev)
  * "stale", we don't bother checking the port ranges against the
  * current socket values.
  */
-static int pcmcia_release_io(struct pcmcia_device *p_dev)
+static void pcmcia_release_io(struct pcmcia_device *p_dev)
 {
 	struct pcmcia_socket *s = p_dev->socket;
-	int ret = -EINVAL;
 	config_t *c;
 
 	mutex_lock(&s->ops_mutex);
@@ -412,8 +411,6 @@ static int pcmcia_release_io(struct pcmcia_device *p_dev)
 
 out:
 	mutex_unlock(&s->ops_mutex);
-
-	return ret;
 } /* pcmcia_release_io */