iio: gyro: adis16130: remove mlock usage

The use of indio_dev's mlock is discouraged. The driver already defines
it's own `bus_lock` in `adis16130_spi_read()`, so using the mlock is
redundant.

The parts supported by this chip are obsoleted anyway, so for now we just
remove mlock as part of a general cleanup, until the driver gets removed.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/gyro/adis16130.c

@@ -76,9 +76,7 @@ static int adis16130_read_raw(struct iio_dev *indio_dev,
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		/* Take the iio_dev status lock */
-		mutex_lock(&indio_dev->mlock);
 		ret = adis16130_spi_read(indio_dev, chan->address, &temp);
-		mutex_unlock(&indio_dev->mlock);
 		if (ret)
 			return ret;
 		*val = temp;