Staging: iio: accel: adis16201: Use sign_extend32 function

Use sign_extned32() for 32 bit sign extending rather than hard coding.
Signed-off-by: Himanshu Jha <himanshujha199640@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/staging/iio/accel/adis16201.c

@@ -173,9 +173,8 @@ static int adis16201_read_raw(struct iio_dev *indio_dev,
 		ret = adis_read_reg_16(st, addr, &val16);
 		if (ret)
 			return ret;
-		val16 &= (1 << bits) - 1;
-		val16 = (s16)(val16 << (16 - bits)) >> (16 - bits);
-		*val = val16;
+
+		*val = sign_extend32(val16, bits - 1);
 		return IIO_VAL_INT;
 	}