scsi: ufs: Rename sdev_ufs_device into ufs_device_wlun

The new name reflects the role of this member variable better: a WLUN
through which the power mode of the UFS device is controlled.

Link: https://lore.kernel.org/r/20220419225811.4127248-17-bvanassche@acm.org


Tested-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>