parse traces from the common clock infrastructure
Created by: kdub
Traces from clock_set_rate, clock_enable, clock_disable need specialized parsing. Add additional feature to parse these traces.
Test: run the 3 new unit tests (nosetests tests/test_common_clk.py)
Change-Id: Ib93b72697fc4d5eb30cffb914bbe0cb4c4cd872d