BACKPORT: FROMGIT: scsi: ufs: Add dev ref clock gating wait time support

In UFS version 3.0, a newly added attribute bRefClkGatingWaitTime defines
the minimum time for which the reference clock is required by device during
transition to LS-MODE or HIBERN8 state. Make this change to reflect the new
requirement by adding delays before turning off the clock.

Link: https://lore.kernel.org/r/1581392451-28743-7-git-send-email-cang@codeaurora.org


Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Reviewed-by: Bean Huo <beanhuo@micron.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>

Bug: 150892981
Change-Id: I33b3c50ae0854621364bb3785c96e951dc7031ef
(cherry picked from commit 09f17791e640dcb8b29cc0b3279e73f48985c2be
https://git.kernel.org/pub/scm/linux/kernel/git/mkp/scsi.git

 5.7/scsi-queue)
[can: Resolved minor conflict in drivers/scsi/ufs/ufshcd.c]
Signed-off-by: Can Guo <cang@codeaurora.org>