Modify CTS test for subtitle to call selectTrack() after prepare().

o selectTrack() API is designed to be called after prepare().

Change-Id: Idd8bc0d803a5309bef63a6e5703064c533436865
(cherry picked from commit 775f97a025724027c0863f6bd88bdef74bef27cc)
diff --git a/tests/tests/media/src/android/media/cts/MediaPlayerTest.java b/tests/tests/media/src/android/media/cts/MediaPlayerTest.java
index d94f4ab..9bc9046 100644
--- a/tests/tests/media/src/android/media/cts/MediaPlayerTest.java
+++ b/tests/tests/media/src/android/media/cts/MediaPlayerTest.java
@@ -758,11 +758,12 @@
             }
         });
 
+        mMediaPlayer.prepare();
+        assertFalse(mMediaPlayer.isPlaying());
+
         mSubtitleStatus.reset();
         selectSubtitleTrack(0);
 
-        mMediaPlayer.prepare();
-        assertFalse(mMediaPlayer.isPlaying());
         mMediaPlayer.start();
         assertTrue(mMediaPlayer.isPlaying());