msm: mct: Add Maximum Current Throttling Driver

Add Maximum Current Throttling (MCT).
MCT driver enables application to turn on/off CPU based current
throttling by setting credit/upper limit in the MCT CPU registers.
MCT limits the maximum amount of power that a CPU may consume over
a period of time.

Change-Id: Ife742a8bdd09398a24c13133fce7a41a79e6b503
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>