Fix RingertoneManagerTest#testStopPreviousRingtone

Bug 2893018

Use adjustStreamVolume to get the device out of vibrate mode,
so that isPlaying will return true when its supposed to.

Change-Id: Ie86b0781d5c39dfcbc6e15c79c07fc67109896bc
diff --git a/tests/tests/media/src/android/media/cts/RingtoneManagerTest.java b/tests/tests/media/src/android/media/cts/RingtoneManagerTest.java
index 31aab6d..dcc45c3 100644
--- a/tests/tests/media/src/android/media/cts/RingtoneManagerTest.java
+++ b/tests/tests/media/src/android/media/cts/RingtoneManagerTest.java
@@ -63,9 +63,7 @@
         mOriginalVolume = mAudioManager.getStreamVolume(AudioManager.STREAM_RING);
         mDefaultUri = RingtoneManager.getActualDefaultRingtoneUri(mContext,
                 RingtoneManager.TYPE_RINGTONE);
-        // set ringer to a reasonable volume
-        int maxVolume = mAudioManager.getStreamMaxVolume(AudioManager.STREAM_RING);
-        mAudioManager.setStreamVolume(AudioManager.STREAM_RING, maxVolume / 2,
+        mAudioManager.adjustStreamVolume(AudioManager.STREAM_RING, AudioManager.ADJUST_RAISE,
                 AudioManager.FLAG_ALLOW_RINGER_MODES);
     }