gpio: mpc8xxx: Slightly update the code for better readability

Setting gc->direction_output to gc->direction_output looks strange.
I think this change makes the intention more clear.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-mpc8xxx.c

@@ -339,8 +339,11 @@ static int mpc8xxx_probe(struct platform_device *pdev)
 	 */
 	mpc8xxx_irq_chip.irq_set_type = devtype->irq_set_type;
 
-	gc->direction_output = devtype->gpio_dir_out ?: gc->direction_output;
-	gc->get = devtype->gpio_get ?: gc->get;
+	if (devtype->gpio_dir_out)
+		gc->direction_output = devtype->gpio_dir_out;
+	if (devtype->gpio_get)
+		gc->get = devtype->gpio_get;
+
 	gc->to_irq = mpc8xxx_gpio_to_irq;
 
 	ret = gpiochip_add_data(gc, mpc8xxx_gc);