gpio: pcie-idio-24: Use -ENOTSUPP consistently

The GPIO library expects the drivers to return -ENOTSUPP in some cases
and not using analogue POSIX code. Make the driver to follow this.
Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: William Breathitt Gray <wbg@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

drivers/gpio/gpio-pcie-idio-24.c

@@ -267,7 +267,7 @@ static int idio_24_reg_mask_xlate(struct gpio_regmap *const gpio, const unsigned
 	case IDIO_24_CONTROL_REG:
 		/* We can only set direction for TTL/CMOS lines */
 		if (offset < 48)
-			return -EOPNOTSUPP;
+			return -ENOTSUPP;
 
 		*reg = IDIO_24_CONTROL_REG;
 		*mask = CONTROL_REG_OUT_MODE;