scsi: ufs-msm: override HS rate series with vendor specifics

High Speed rate series might always be set to rate "A" if the
vendor doesn't specify any rate during pre-power change notify.

Change-Id: Ied7ce3eba98ffbece97ec06eb6cab8df1d104f52
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>