Support for PMU event counters
Created by: bea-arm
Add support for reading Arm PMU event counters through perf framework and expose the readings as a dedicated ftrace event.
This is being achieved by introducing new feature to the sched_tp kernel module for tracing the PMU event counters, plus changes to the lisa/tests/base.py, that handle the post-processing for CPU_CYCLES counter events, which allows drawing conclusions on the estimated CPU frequency.
Additionally both util_tracking and load_tracking tests get amended to benefit from the above mentioned changes.