scsi: ufs: enable hibern8 during clk gating

This change enables hibern8 during clock gating to let driver issue
hibern8 enter during clock gating before power collapse and issue hibern8
exit during clock un-gate after power un-collapse regardless of auto
hibern8 support.

Change-Id: Ib8cb4cb010f673eda7d86eb456706bf2c8fb4676
Signed-off-by: Can Guo <cang@codeaurora.org>