msm: thermal: Add RT priority to kernel thermal threads

Add RT priority to KTM frequency mitigation thread. This
is required since we have seen cases where this thread
is not scheduled fast enough during high temperature rampup
that lead to thermal runaway. So this change would make sure
the thermal frequency mitigation thread gets high priority
and mitigate core as soon as a temperature threshold is triggered.

Change-Id: Ie8a6fd80fb8e9bdb894a26a8bf7abd159a3f3bce
Signed-off-by: Shiju Mathew <shijum@codeaurora.org>