power: supply: bq27xxx: Move one time design full read out of poll

This value only needs read once. Move that read into the function
that returns the value to keep the logic all in one place. This
also avoids doing this check every time we read in values in
the device update poll worker.

While here, correct this function's error message.
Signed-off-by: Andrew Davis <afd@ti.com>
Link: https://lore.kernel.org/r/20240123150914.308510-5-afd@ti.comSigned-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/bq27xxx_battery.c

@@ -1595,17 +1595,24 @@ static inline int bq27xxx_battery_read_fcc(struct bq27xxx_device_info *di)
  * Return the Design Capacity in µAh
  * Or < 0 if something fails.
  */
-static int bq27xxx_battery_read_dcap(struct bq27xxx_device_info *di)
+static int bq27xxx_battery_read_dcap(struct bq27xxx_device_info *di,
+				     union power_supply_propval *val)
 {
 	int dcap;
 
+	/* We only have to read charge design full once */
+	if (di->charge_design_full > 0) {
+		val->intval = di->charge_design_full;
+		return 0;
+	}
+
 	if (di->opts & BQ27XXX_O_ZERO)
 		dcap = bq27xxx_read(di, BQ27XXX_REG_DCAP, true);
 	else
 		dcap = bq27xxx_read(di, BQ27XXX_REG_DCAP, false);
 
 	if (dcap < 0) {
-		dev_dbg(di->dev, "error reading initial last measured discharge\n");
+		dev_dbg(di->dev, "error reading design capacity\n");
 		return dcap;
 	}
 
@@ -1614,7 +1621,12 @@ static int bq27xxx_battery_read_dcap(struct bq27xxx_device_info *di)
 	else
 		dcap *= 1000;
 
-	return dcap;
+	/* Save for later reads */
+	di->charge_design_full = dcap;
+
+	val->intval = dcap;
+
+	return 0;
 }
 
 /*
@@ -1865,10 +1877,6 @@ static void bq27xxx_battery_update_unlocked(struct bq27xxx_device_info *di)
 		 */
 		if (!(di->opts & BQ27XXX_O_ZERO))
 			bq27xxx_battery_current_and_status(di, NULL, &status, &cache);
-
-		/* We only have to read charge design full once */
-		if (di->charge_design_full <= 0)
-			di->charge_design_full = bq27xxx_battery_read_dcap(di);
 	}
 
 	if ((di->cache.capacity != cache.capacity) ||
@@ -2062,7 +2070,7 @@ static int bq27xxx_battery_get_property(struct power_supply *psy,
 		ret = bq27xxx_simple_value(di->cache.charge_full, val);
 		break;
 	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
-		ret = bq27xxx_simple_value(di->charge_design_full, val);
+		ret = bq27xxx_battery_read_dcap(di, val);
 		break;
 	/*
 	 * TODO: Implement these to make registers set from