msm8974: remove network modes overlay

Change-Id: I47ffd75fe0fccf85c903652b5e0789ad57510ed1
Fix audio context  sepolicy error

  * As we don't use CM's sepolicy we need this to be declared in device repo

Change-Id: If63e4473d41a64897f4d1cbf16a23badad37607e
Signed-off-by: Josue Rivera <prbassplayer@gmail.com>