Init haptic intensity for the first fast track.

The haptic intensity for fast track should be initialized, or it will be
HAPTIC_SCALE_MUTE by default, which may result in no haptics.

Bug: 130312331
Test: play haptics stream with FastMixer enabled
Change-Id: If5a1ea12c563c4af1422b2e32451b80e69d2ef58
1 file changed