The accel_3d sensor already has a timestamp channel, this patch just
replicate that for gravity sensor.
Signed-off-by: NYe Xiang <xiang.ye@intel.com>
Link: https://lore.kernel.org/r/20210105093515.19135-2-xiang.ye@intel.comSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>