mips: ar7: add missing iounmap() on error in ar7_gpio_init

Add the missing iounmap() of gpch->regs before return from
ar7_gpio_init() in the error handling case.
Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/ar7/gpio.c

@@ -319,6 +319,7 @@ int __init ar7_gpio_init(void)
 	if (ret) {
 		printk(KERN_ERR "%s: failed to add gpiochip\n",
 					gpch->chip.label);
+		iounmap(gpch->regs);
 		return ret;
 	}
 	printk(KERN_INFO "%s: registered %d GPIOs\n",