midi audio: allow midi restart even upon stop state

Due to the limitation of EAS_XXX interfaces design, there's no way to
restart midi playback again once last track reaches EOS. To allow this
operation, seek the current track backwards and resume again.

Change-Id: Ib93993eb18e309ac7cb2a305d55ab63f2e86acb9
(cherry picked from commit 233de835)