iio: adis16480: fix devices that do not support sleep mode

iio: adis16480: fix devices that do not support sleep mode

Not all devices supported by this driver support being put to sleep
mode. For those devices, when calling 'adis16480_stop_device()' on the
unbind path, we where actually writing in the SYNC_SCALE register.

Fixes: 654096028a0cf ("iio: imu: adis16480: Add support for ADIS16490")
Fixes: a050491a81b0b ("iio: imu: adis16480: Add support for ADIS1649x family of devices")
Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20210903141423.517028-6-nuno.sa@analog.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>