usb: typec: class: Unlocked on error in typec_register_partner()

We recently added some locking to this function but this error path
was accidentally missed.  Unlock before returning.

Fixes: ec27386 ("usb: typec: class: Fix NULL pointer access")
Cc: stable <stable@kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/Z_44tOtmml89wQcM@stanley.mountain
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Dan Carpenter

drivers/usb/typec/class.c

@@ -1056,6 +1056,7 @@ struct typec_partner *typec_register_partner(struct typec_port *port,
 	ret = device_register(&partner->dev);
 	if (ret) {
 		dev_err(&port->dev, "failed to register partner (%d)\n", ret);
+		mutex_unlock(&port->partner_link_lock);
 		put_device(&partner->dev);
 		return ERR_PTR(ret);
 	}