Making sure mediaserver can write into foreground cpuset

If multiple writepids, all must be in one line to take effect.
Else, only the last one will take effect.

bug: 30192722
bug: 28312446

Change-Id: I35eea3f604fb5f0c2c0a6bce9e22cfde9d5805a9
diff --git a/media/mediaserver/mediaserver.rc b/media/mediaserver/mediaserver.rc
index faab938..f6c325c 100644
--- a/media/mediaserver/mediaserver.rc
+++ b/media/mediaserver/mediaserver.rc
@@ -3,5 +3,4 @@
     user media
     group audio camera inet net_bt net_bt_admin net_bw_acct drmrpc mediadrm
     ioprio rt 4
-    writepid /dev/cpuset/foreground/tasks
-    writepid /dev/stune/foreground/tasks
+    writepid /dev/cpuset/foreground/tasks /dev/stune/foreground/tasks