Only change usecase to ultra-low-latency-playback if it's enabled

This fixes audio playback on kltevzw, and probably others

Change-Id: I1ca55c9fc5de0758930bc32971f53fb36f80920b
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_hardware_qcom_audio-caf into cm-11.0