msm: thermal: Refactor core control mitigation only for smp

Refactor core control mitigation only for smp target otherwise it
leads to compilation issue for non smp since cpu_up and cpu_down
functions are not defined.

Change-Id: I73d3792fd9c4ce6d16132b55eb2446dd4bcdfbce
Signed-off-by: Anji Jonnala <anjir@codeaurora.org>