blue-common: remove voip device and QCOM-specific flag from audio_policy

The non-extistent flag AUDIO_DEVICE_OUT_COMMUNICATION will cause
AudioPolicyManager to ignore the "primary" device, leading to
broken audio system.
voip_tx has only one COMMUNICATION device defined, so I removed it
with voip_rx altogether.

Change-Id: Ie3470fff7a88bca77e79070d38988dd84f3aceca