DVFS: cannot suspend/resume at all OPPs
Doing a suspend/resume at arbitrary OPPs seems unstable.
In addition, the firmware detects the OPP upon entering suspend, but may also change it during resume making Linux's notion of the OPP out of sync with hardware, and causing subsequent OPP changes to hang.
Might need to hard-code suspend-opp
in the DT to enforce specific OPPs during suspend/resume.