staging: iio: accel: adis16201: remove iio_dev mlock

In the driver adis16201 read raw does not require an iio_dev->mlock for
reads. It can run concurrently as adis_read_reg_16() is protected by a
transaction lock.

Signed-off-by: Aishwarya Pant <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/staging/iio/accel/adis16201.c

···
 		default:
 			return -EINVAL;
 		}
-		mutex_lock(&indio_dev->mlock);
 		addr = adis16201_addresses[chan->scan_index];
 		ret = adis_read_reg_16(st, addr, &val16);
-		if (ret) {
-			mutex_unlock(&indio_dev->mlock);
+		if (ret)
 			return ret;
-		}
 		val16 &= (1 << bits) - 1;
 		val16 = (s16)(val16 << (16 - bits)) >> (16 - bits);
 		*val = val16;
-		mutex_unlock(&indio_dev->mlock);
 		return IIO_VAL_INT;
 	}
 	return -EINVAL;