Revert "Don't set TARGET_ENABLE_QC_AV_ENHANCEMENTS for msm8960 devices"

It can be enabled again after hardware/qcom/media update.

This reverts commit 2400c782634f11a1666a56c5e16b66300b3bd0f8.

Change-Id: I4b16b8d7111b23d11fa81d44b773e334817b2a89