iio: accel: mma9551_core: Prevent uninitialized variable in mma9551_read_config_word()

Smatch Warns:
drivers/iio/accel/mma9551_core.c:299
	mma9551_read_config_word() error: uninitialized symbol 'v'.

When (offset >= 1 << 12) is true mma9551_transfer() will return -EINVAL
without 'v' being initialized, so check for the error and return.

Note: No actual bug as caller checks the return value and does not
use the parameter in the problem case.
Signed-off-by: NHarshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Link: https://lore.kernel.org/r/20230126153610.3586243-1-harshit.m.mogalapalli@oracle.comSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/accel/mma9551_core.c

@@ -296,9 +296,12 @@ int mma9551_read_config_word(struct i2c_client *client, u8 app_id,
 
 	ret = mma9551_transfer(client, app_id, MMA9551_CMD_READ_CONFIG,
 			       reg, NULL, 0, (u8 *)&v, 2);
+	if (ret < 0)
+		return ret;
+
 	*val = be16_to_cpu(v);
 
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL_NS(mma9551_read_config_word, IIO_MMA9551);