gpio: regmap: 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 <[e-mail]>
Reviewed-by: Michael Walle <[e-mail]>
Reviewed-by: Linus Walleij <[e-mail]>
Signed-off-by: Bartosz Golaszewski <[e-mail]>

drivers/gpio/gpio-regmap.c

···
 		base = gpio_regmap_addr(gpio->reg_dir_in_base);
 		invert = 1;
 	} else {
-		return -EOPNOTSUPP;
+		return -ENOTSUPP;
 	}
 
 	ret = gpio->reg_mask_xlate(gpio, base, offset, &reg, &mask);
···
 		base = gpio_regmap_addr(gpio->reg_dir_in_base);
 		invert = 1;
 	} else {
-		return -EOPNOTSUPP;
+		return -ENOTSUPP;
 	}
 
 	ret = gpio->reg_mask_xlate(gpio, base, offset, &reg, &mask);