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: NAlexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>