power: supply: bq27xxx_battery: Silence deferred-probe error

The driver fails to probe with -EPROBE_DEFER if battery's power supply
(charger driver) isn't ready yet and this results in a bit noisy error
message in KMSG during kernel's boot up. Let's silence the harmless
error message.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Andrew F. Davis <afd@ti.com>
Reviewed-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/bq27xxx_battery.c

@@ -1885,7 +1885,10 @@ int bq27xxx_battery_setup(struct bq27xxx_device_info *di)
 
 	di->bat = power_supply_register_no_ws(di->dev, psy_desc, &psy_cfg);
 	if (IS_ERR(di->bat)) {
-		dev_err(di->dev, "failed to register battery\n");
+		if (PTR_ERR(di->bat) == -EPROBE_DEFER)
+			dev_dbg(di->dev, "failed to register battery, deferring probe\n");
+		else
+			dev_err(di->dev, "failed to register battery\n");
 		return PTR_ERR(di->bat);
 	}