sepolicy: allow AAudio apps to use FDs from the audio HAL

The API does not expose the FD directly. But they are
used by libaaudio.so linked with the app.

Needed for low latency audio.

Bug: 37167970
Test: NativeOboe touch to tone latency app
Change-Id: I92372eff44d856e9aff399dc9c64fd18524fdc44
Signed-off-by: Phil Burk <philburk@google.com>