audio_effects.conf - Add loudness enhancer

This was added to the default audio_effects.conf in KitKat, but
the DSPManager override still doesn't have it.

Change-Id: I7dbc97fb76a188df385d2e73c769b7aade9baa82
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_packages_apps_DSPManager into kitkat