ptp: switch to use gpiolib

This platform supports gpiolib, so remove the custom API use
and replace with calls to gpiolib. Also request the GPIO before
starting to use it.

Cc: Imre Kaloz <kaloz@openwrt.org>
Cc: Alexandre Courbot <acourbot@nvidia.com>
Cc: netdev@vger.kernel.org
Acked-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Krzysztof Halasa <khc@pm.waw.pl>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/ptp/ptp_ixp46x.c

@@ -259,8 +259,15 @@ static struct ixp_clock ixp_clock;
 static int setup_interrupt(int gpio)
 {
 	int irq;
+	int err;
 
-	gpio_line_config(gpio, IXP4XX_GPIO_IN);
+	err = gpio_request(gpio, "ixp4-ptp");
+	if (err)
+		return err;
+
+	err = gpio_direction_input(gpio);
+	if (err)
+		return err;
 
 	irq = gpio_to_irq(gpio);