Remove proc access from hal_audio.

As a consequence, hal_audio_default (and any domain with hal_audio attribute)
loses access to proc label.

Bug: 65643247
Test: sailfish boots, can play sound through speakers and headset
(3.5mm, usb, and bluetooth) without denials from hal_audio to proc.
Test: VtsHalAudioEffectV2_0Target
Test: VtsHalAudioV2_0Target

Change-Id: I3eead5a26ef36b8840d31c5e078f006b0c2266a3