audio-hal: fix a2dp mute issue

Playback usecase on a2dp path is muting if its enabled
while usecase on bt sco mic is still active.
To fix this, avoid enabling record usecase on SCO device
when A2DP device is in ready state.

Change-Id: Id6d926096fd35a1f0d3b60b3f10dc8c39f2cb225