power: supply: axp288_fuel_gauge: Fix fuel_gauge_reg_readb return on error

If reading the register fails, return the actual error code, instead
of the uninitialized val variable;
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

drivers/power/supply/axp288_fuel_gauge.c

@@ -169,8 +169,10 @@ static int fuel_gauge_reg_readb(struct axp288_fg_info *info, int reg)
 			break;
 	}
 
-	if (ret < 0)
+	if (ret < 0) {
 		dev_err(&info->pdev->dev, "axp288 reg read err:%d\n", ret);
+		return ret;
+	}
 
 	return val;
 }