staging: mt7621-gpio: use GPIOF_DIR_OUT and GPIOF_DIR_IN macros instead of custom values

There are macros in gpio kernel's headers to define direction
of a gpio. Use them instead of return custom '0' and '1' values.
Signed-off-by: NSergio Paracuellos <sergio.paracuellos@gmail.com>
Reviewed-by: NNeilBrown <neil@brown.name>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-gpio/gpio-mt7621.c

@@ -6,6 +6,7 @@
 
 #include <linux/io.h>
 #include <linux/err.h>
+#include <linux/gpio.h>
 #include <linux/gpio/driver.h>
 #include <linux/module.h>
 #include <linux/of_irq.h>
@@ -127,7 +128,7 @@ mediatek_gpio_get_direction(struct gpio_chip *chip, unsigned int offset)
 	struct mtk_gc *rg = to_mediatek_gpio(chip);
 	u32 t = mtk_gpio_r32(rg, GPIO_REG_CTRL);
 
-	return (t & BIT(offset)) ? 0 : 1;
+	return (t & BIT(offset)) ? GPIOF_DIR_OUT : GPIOF_DIR_IN;
 }
 
 static int