Fix TuneIn app helper to account for feedback pop-up

1. After stopping playing the radio, sometimes there is a pop-up message
asking for feedback.  It was checked in the wrong place in stopChannel().

2. When the feedback pop-up appears, the final radio-stop check object
becomes stale, and throws an exception.  This check is not neccessary,
and it prevents the DoU test from properly exiting the app, resulting
in higher power in subsequent power test.  Removing this radio-stop
check.

Change-Id: Ie41b792bdeebd3ebaa35eb22ae51e4f85817597c