gpio: renamed "-v"-parameter to "-e" (refs #39954)

* renamed the "-v"-parameter to specify the value to be set/expected to "-e" instead to fix a parameter collision with "-v" for verbose output.
* replace usage of "-v"-paramter in runtest files with new "-e"-paramter

Change-Id: I9c31d2d3840ce9e1a1ba0baa1f5fecf76188fa5b