msm: thermal: Update to read CPU freq table from OPP

Remove workaround in KTM to read CPU freq table by
explicitly online a core if it is offline during
KTM init. Update KTM to rely on OPP to read CPU
freq table. OPP doesn't require the CPU's to be
online atleast once to populate frequency table.

Change-Id: I4a3036742f6805900a36e092ec07a3dabcce0db8
Signed-off-by: Shiju Mathew <shijum@codeaurora.org>