scsi: ufs: add UFS power collapse support during hibern8

UFS host controller hardware may allow the host controller
to be power collapsed when UFS link is hibern8 state, this
change allows the UFS host controller to be power collapsed
during hibern8.

Change-Id: I42f962484b9d6635be1139b1fc6447dd2ca2200c
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
[subhashj@codeaurora.org: resolved trivial merge conflicts]
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
[venkatg@codeaurora.org: resolved trivial merge conflicts]
Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
[cang@codeaurora.org: Resolved trivial merge conflicts]
Signed-off-by: Can Guo <cang@codeaurora.org>