power: supply: max17042_battery: Add support for the TTE_NOW prop

The max170{42,47,50,55} family of fuel gauges all provide time-to-empty
estimation. As such, let's export this as a property.

Signed-off-by: Geordan Neukum <[e-mail]>
Signed-off-by: Sebastian Reichel <[e-mail]>

drivers/power/supply/max17042_battery.c

···
 	POWER_SUPPLY_PROP_SCOPE,
 	POWER_SUPPLY_PROP_CURRENT_NOW,
 	POWER_SUPPLY_PROP_CURRENT_AVG,
+	POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW,
 };
 
 static int max17042_get_temperature(struct max17042_chip *chip, int *temp)
···
 		} else {
 			return -EINVAL;
 		}
+		break;
+	case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
+		ret = regmap_read(map, MAX17042_TTE, &data);
+		if (ret < 0)
+			return ret;
+
+		val->intval = data * 5625 / 1000;
 		break;
 	default:
 		return -EINVAL;