hal_audio: Allow writing dump info into pipes when capturing BR

The following HAL methods use file descriptors to write dump
info comprising audioflinger debug dump:

IDevice.debugDump
IEffectsFactory.debugDump
IStream.debugDump

Bug: 37993476
Test: check contents of media.audio_flinger section in
      a bugreport captured on Pixel device

Change-Id: I77d347c019ac93c3ba0d54ce50f0fdc243b04685

public/hal_audio.te

@@ -17,6 +17,8 @@ allow hal_audio audio_device:chr_file rw_file_perms;
 # Needed to provide debug dump output via dumpsys' pipes.
 allow hal_audio shell:fd use;
 allow hal_audio shell:fifo_file write;
+allow hal_audio dumpstate:fd use;
+allow hal_audio dumpstate:fifo_file write;
 
 # Needed on some devices for playing audio on paired BT device,
 # but seems appropriate for all devices.