regmap: Add support for 24 bit wide register addresses

Since regmap already has support for formatting 24 bit wide values, so adding
support for 24 bit wide registers is pretty much straight forward.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/base/regmap/regmap.c

@@ -500,6 +500,12 @@ struct regmap *regmap_init(struct device *dev,
 		}
 		break;
 
+	case 24:
+		if (reg_endian != REGMAP_ENDIAN_BIG)
+			goto err_map;
+		map->format.format_reg = regmap_format_24;
+		break;
+
 	case 32:
 		switch (reg_endian) {
 		case REGMAP_ENDIAN_BIG: