nuplayer: Do not notify EOS when paused

-Playback switches to next clip if a paused clip is seeked to EOS.
-Audio drain is allowed to fill buffer when paused. During drain,
EOS is notified even during paused state and playback switches to
next clip.
-Avoid notifying EOS when paused.

Change-Id: I8261219615f4ce726e03d02b0cb3e71889a711d0