scsi: ufs: Put HBA into LPM during clk gating

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

Link: https://lore.kernel.org/r/52198e70bff750632740d78678a815256d697e43.1603825776.git.asutoshd@codeaurora.org


Reviewed-by: Avri Altman <avri.altman@wdc.com>
Acked-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>