msm: pm-8x60: Do not default to WFI when not enabled

Return MSM_PM_SLEEP_MODE_NOT_SELECTED in msm_pm_idle_prepare as the
default mode instead of WFI. Skip enter low power mode when this
mode is selected.

Change-Id: Id4a07ba1353b358726c81ed441e0327a9154de8a
Signed-off-by: Priyanka Mathur <pmathur@codeaurora.org>
d2: Update cpuidle state latencies and power

 * Commit 9bf715677c214c53577261e8e4173d7f4f2157df updated the latency
   and power values for all boards, but this change was not carried over
   to the D2 board files.
 * Update the board files per QC to enable new power modes.

Change-Id: Iec1c81ee46eea4d3e96f2be7184bc49456888e78