Extend access to proc/asound/*

Renamed this type:
proc_asound_cards -> proc_asound

Labeled /proc/asound/devices as proc_asound.

We now use proc_asound type to label files under /proc/asound which we
want to expose to system components.

Bug: 66988327
Test: Pixel 2 boots, can play sound with or without headphones, and
selinux denials to proc_asound are not seen.

Change-Id: I453d9bfdd70eb80931ec9e80f17c8fd0629db3d0