Update doc for audio-coupled-haptic related stuff.

When using audio-coupled-haptic playback, the haptic channels will be
muted if the app doesn't have the vibrate permission. Update the doc to
state that apps should hold vibrate permission to make
audio-coupled-haptic works as expected.

Bug: 236586224
Test: make
Change-Id: I69c1332d39f997a61f3a969d652144d829de9659

media/java/android/media/AudioAttributes.java

@@ -1200,6 +1200,8 @@ public final class AudioAttributes implements Parcelable {
         /**
          * Specifying if haptic should be muted or not when playing audio-haptic coupled data.
          * By default, haptic channels are disabled.
+         * <p>This will be ignored if the caller doesn't have the
+         * {@link android.Manifest.permission#VIBRATE} permission.
          * @param muted true to force muting haptic channels.
          * @return the same Builder instance.
          */

media/java/android/media/audiofx/HapticGenerator.java

@@ -91,7 +91,8 @@ public class HapticGenerator extends AudioEffect implements AutoCloseable {
     }
 
     /**
-     * Enable or disable the effect.
+     * Enable or disable the effect. The effect can only be enabled if the caller has the
+     * {@link android.Manifest.permission#VIBRATE} permission.
      *
      * @param enabled the requested enable state
      * @return {@link #SUCCESS} in case of success, {@link #ERROR_INVALID_OPERATION}