pulseaudio: make it work out of the box

pulseaudio: make it work out of the box

* reuse 'audio' group as access group

  The current failure is:

  root@usrp-e1xx:/etc/pulse# pulseaudio --system
   [..]
  W: protocol-native.c: Failed to get GID of group 'pulse-access'
  W: protocol-native.c: Failed to check group membership.
  W: protocol-native.c: Denied access to client with invalid authorization data.

* add more required modules

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>