gpio: crystalcove: 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 <andriy.shevchenko@linux.intel.com>

drivers/gpio/gpio-crystalcove.c

@@ -92,7 +92,7 @@ static inline int to_reg(int gpio, enum ctrl_register reg_type)
 		case 0x5e:
 			return GPIOPANELCTL;
 		default:
-			return -EOPNOTSUPP;
+			return -ENOTSUPP;
 		}
 	}