gpio: dwapb: Fix error handling in dwapb_gpio_probe()

If dwapb_gpio_add_port() fails in dwapb_gpio_probe(),
gpio->clk is left undisabled.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-dwapb.c

@@ -728,6 +728,7 @@ static int dwapb_gpio_probe(struct platform_device *pdev)
 out_unregister:
 	dwapb_gpio_unregister(gpio);
 	dwapb_irq_teardown(gpio);
+	clk_disable_unprepare(gpio->clk);
 
 	return err;
 }