power: supply: cpcap-charger: Improve battery detection

We are currently using a wrong ADC range for the battery detection.
The ADC returns the battery temperature if connected.

Cc: Merlijn Wajer <merlijn@wizzup.org>
Cc: Pavel Machek <pavel@ucw.cz>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/cpcap-charger.c

@@ -176,20 +176,21 @@ static enum power_supply_property cpcap_charger_props[] = {
 	POWER_SUPPLY_PROP_CURRENT_NOW,
 };
 
+/* No battery always shows temperature of -40000 */
 static bool cpcap_charger_battery_found(struct cpcap_charger_ddata *ddata)
 {
 	struct iio_channel *channel;
-	int error, value;
+	int error, temperature;
 
 	channel = ddata->channels[CPCAP_CHARGER_IIO_BATTDET];
-	error = iio_read_channel_raw(channel, &value);
+	error = iio_read_channel_processed(channel, &temperature);
 	if (error < 0) {
 		dev_warn(ddata->dev, "%s failed: %i\n", __func__, error);
 
 		return false;
 	}
 
-	return value == 1;
+	return temperature > -20000 && temperature < 60000;
 }
 
 static int cpcap_charger_get_charge_voltage(struct cpcap_charger_ddata *ddata)