scsi : ufs-qcom: Add provision to set qcom specific supplies in LPM

While UFS is configured for sleep mode during APSS power collapse
(with spm_lvl=3), UFS driver votes-on for PX10 supply (which drives
IO Pads and Reset line) even during suspend. Usually it votes PX10
with 100uA load all the time. On most of the targets, this load
(100uA) is sufficient to keep the supply in LPM mode.

But on some targets any load value other than 0, forces the supply to
HMP mode, On such targets PX10 supply may cause more power leakage in
RBSC scenario.

So add provision to supply minimum load from device-tree, and set
explicit load during suspend/resume. On targets where explicit 0 load
is needed, it can be supplied from device tree.

This logic is present for regular UFS supplies. Same logic is being
extended to qcom specific supplies.

Change-Id: Ic81582e9add10864f81181af5f84701febb97aef
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>