msm: thermal: Update frequency plan for offline clusters

Update frequency plan for offline clusters by
onlining a core in the cluster and after reading
the frequency plan put the core back in offline.

CRs-fixed: 705769
Change-Id: I0cf439a2a14fc0923d4018cc43beeda809be2373
Signed-off-by: Shiju Mathew <shijum@codeaurora.org>