scsi: ufs: Rework ufshcd_change_queue_depth()

Prepare for making sdev->host->can_queue less than hba->nutrs. This patch
does not change any functionality.

Link: https://lore.kernel.org/r/20211203231950.193369-9-bvanassche@acm.org


Tested-by: Bean Huo <beanhuo@micron.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>