msm: thermal: Add RT priority to kernel hotplug thread

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

Change-Id: I72ecf69ede0444fe74fd9c4eaf40a12e8734326c
Signed-off-by: Shiju Mathew <shijum@codeaurora.org>