PM / devfreq: Introduce MSM CCI HWmon device

CCI400 on MSM has additional PMU counters that can be used to monitor
cache requests. MSM CCI hardware monitor device configures these
registers to monitor cache and inform governor. It can also set an
IRQ when count exceeds a programmable limit.

Change-Id: I1d80f57749b91c3972e60e54c75226c4d49d2ec6
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>