pinctrl: fix mutex deadlock in get_pinctrl_dev_from_of_node()

This obvious bug was introduced by d755910b7 ("pinctrl: move subsystem
mutex to pinctrl_dev struct").
Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/core.c

@@ -129,7 +129,7 @@ struct pinctrl_dev *get_pinctrl_dev_from_of_node(struct device_node *np)
 			return pctldev;
 		}
 
-	mutex_lock(&pinctrldev_list_mutex);
+	mutex_unlock(&pinctrldev_list_mutex);
 
 	return NULL;
 }