audioserver.rc: start audioserver earlier

We have seen sometimes SystemServer's StartAudioService wait for native
audio policy service.
This CL will move audioserver to be started on "boot" trigger of init.rc
where class 'hal' is started and data/ access are also ready, so it will
give audioserver more time to initialize to avoid service backoff.

Bug: 64218899
Test: 50 reboot cycles on Taimen
Change-Id: Ic220eb74a7a0df64b531a28c7b9d6fb6d38d3699

media/audioserver/audioserver.rc

@@ -1,5 +1,5 @@
 service audioserver /system/bin/audioserver
-    class main
+    class core
     user audioserver
     # media gid needed for /dev/fm (radio) and for /data/misc/media (tee)
     group audio camera drmrpc inet media mediadrm net_bt net_bt_admin net_bw_acct