msm: thermal: check LMH DCVS devicetree to enable reboot/suspend mitigation

KTM suspend/reboot frequency mitigation is not required for target
which has LMH DCVS hardware support. lmh_dcvs_available flag in the
KTM is initialized only post OSM driver is up. But during KTM probe,
it checks this flag to register suspend/reboot notifier. Since
it is not initialized, it always register with these notifier and
does frequency mitigation whenever it notifies KTM.

To avoid this, check if the LMH DCVS related devicetree node is
enabled during KTM probe before enabling suspend/reboot notifier
registration. To be safe use the same check in CPU frequency policy
callback for KTM max cpu frequency request as well.

Change-Id: I337477dd296e1e681498d702ab03c164d7554186
Signed-off-by: Manaf Meethalavalappu Pallikunhi <manafm@codeaurora.org>