PowerLog: Update interface and tests for log plot

The log plot should be an option for the powerlog.
This defaults to true if unspecified (compatibility).
Update the unit tests so that they now pass.

Test: atest powerlog_tests
Test: atest powerlog_tests --host
Bug: 180428390
Change-Id: I512ce382eb93b9d6b9e7e31c81efba5f6ccf8353
3 files changed