scsi: ufs: Put hba into LPM during clk gating

During clock gating, after clocks are disabled, put hba into LPM to save
more power.

Change-Id: I1d8d76f3b72a2346c9ab6268555b0b416cb3b16f
Signed-off-by: Can Guo <cang@codeaurora.org>