Re: No mute state in volume context changes on abs devices

Since we are not muting the external audio device when ADJUST_MUTE is
called we should not change the volume based on the mute state in the
volume context switch callback

Test: play music -> call -> drop call -> check vol (with A2DP and LEA)
Bug: 399278432
Flag: EXEMPT bugfix
Change-Id: Ic8cbcebc6ecee087b87d9a0d981083a8f361997d