bq27x00_battery: Fix error return code

Initialize return variable before exiting on an error path.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
(
if@p1 (\(ret < 0\|ret != 0\))
 { ... return ret; }
|
ret@p1 = 0
)
... when != ret = e1
    when != &ret
*if(...)
{
  ... when != ret = e2
      when forall
 return ret;
}

// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>

drivers/power/bq27x00_battery.c

@@ -814,7 +814,8 @@ static int bq27x00_battery_probe(struct i2c_client *client,
 	di->bat.name = name;
 	di->bus.read = &bq27x00_read_i2c;
 
-	if (bq27x00_powersupply_init(di))
+	retval = bq27x00_powersupply_init(di);
+	if (retval)
 		goto batt_failed_3;
 
 	i2c_set_clientdata(client, di);