Fix flake8 checking issue in powervc-driver and Unittest

There are some flake8 issues in each component that are not based
 on coding style rules .
And There are some unittest issues in some component that need to
 be fixed

Change-Id: Ic9a3f2c3b779ced225a42f69a495a606cb62517e
Closes-Bug: #1350160
Merge "Fix flake8 checking issue in powervc-driver and Unittest"