scsi: ufs: Correct the LUN used in eh_device_reset_handler() callback

Users can initiate resets to specific SCSI device/target/host through
IOCTL. When this happens, the SCSI cmd passed to eh_device/target/host
_reset_handler() callbacks is initialized with a request whose tag is -1.
In this case it is not right for eh_device_reset_handler() callback to
count on the LUN get from hba->lrb[-1]. Fix it by getting LUN from the SCSI
device associated with the SCSI cmd.

Link: https://lore.kernel.org/r/1609157080-26283-1-git-send-email-cang@codeaurora.org
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
