gpiolib: remove warnning of allocations with IRQs disabled

Move of_gpiochip_add outof spin_lock, since kzalloc inside
of_gpiochip_add -> of_gpiochip_add_pin_range -> gpiochip_add_pin_range -> kzalloc

WARNING: at kernel/lockdep.c:2740 lockdep_trace_alloc+0xf8/0xfc()
DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))

Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

@@ -1214,15 +1214,14 @@ int gpiochip_add(struct gpio_chip *chip)
 		}
 	}
 
+	spin_unlock_irqrestore(&gpio_lock, flags);
+
 #ifdef CONFIG_PINCTRL
 	INIT_LIST_HEAD(&chip->pin_ranges);
 #endif
 
 	of_gpiochip_add(chip);
 
-unlock:
-	spin_unlock_irqrestore(&gpio_lock, flags);
-
 	if (status)
 		goto fail;
 
@@ -1235,6 +1234,9 @@ unlock:
 		chip->label ? : "generic");
 
 	return 0;
+
+unlock:
+	spin_unlock_irqrestore(&gpio_lock, flags);
 fail:
 	/* failures here can mean systems won't boot... */
 	pr_err("gpiochip_add: gpios %d..%d (%s) failed to register\n",