scsi: ufs: Keep UniPro in FASTMODE

During FASTAUTO operation, device Rx turns on/off frequently.
This generates noise to internal mPHY power.

Keep UniPro in FASTMODE to avoid stability issue.

Bug: 145560423
Bug: 146108838
Bug: 145883809
Change-Id: I1c3b9d22250b7998030c137e5f240091a4f45e81
Signed-off-by: Randall Huang <huangrandall@google.com>
Signed-off-by: Alexander Winkowski <dereference23@outlook.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>