msm: dcvs: start and stop temp updates with core sink

Temperature updates should not be sent continuously just
because a core has registered with dcvs. Instead, start
and stop the updates when the core starts and stops as a
dcvs frequency sink.

Change-Id: If7721f523eb44026c421dd7ec4fa3975bc65cd09
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>