regmap: Devices using format_write don't support bulk operations

Set the use_single_rw flag for devices that use format_write() since
format_write() doesn't support any form of block operation.
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

drivers/base/regmap/regmap.c

@@ -341,6 +341,9 @@ struct regmap *regmap_init(struct device *dev,
 		break;
 	}
 
+	if (map->format.format_write)
+		map->use_single_rw = true;
+
 	if (!map->format.format_write &&
 	    !(map->format.format_reg && map->format.format_val))
 		goto err_map;