msm: boards: Enable Krait Retention.

Add SPM sequences to do Krait retention for 8960,8930
and 8064. Also added a new rpmrs level containing the
latencies and power measurements for this new low power
state.
CRs-Fixed: 369864

Change-Id: I321fa22ab891b929366444f6187876c57f87c421
Signed-off-by: Anji Jonnala <anjir@codeaurora.org>