msm: thermal: Automate KTM's switch to interrupt mode

Add support to Kernel Thermal Monitor (KTM) to stop polling
the temperatures and switch to interrupt mode when the KTM
module init is called. This avoids KTM's dependency on
thermal-engine to notify when to switch to interrupt mode.

After switching to interrupt mode, the KTM spawns a
thermal monitor thread and registers temperature
thresholds for monitoring the vdd restriction.

CRs-Fixed: 567187
Change-Id: Ib1536c9fc32d3fc0ef2737818c39ca80c5d636d8
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>