rootdir: init.rc: Enable I/O priorities for media server and vold

Sets the media-server to class 'real-time' pri 4, and vold to class 'best effort'
pri 2

Signed-off-by: San Mehat <san@google.com>
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 059ac0a..7b7d7ba 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -281,6 +281,7 @@
 
 service vold /system/bin/vold
     socket vold stream 0660 root mount
+    ioprio be 2
 
 service netd /system/bin/netd
     socket netd stream 0660 root system
@@ -302,6 +303,7 @@
 service media /system/bin/mediaserver
     user media
     group system audio camera graphics inet net_bt net_bt_admin
+    ioprio rt 4
 
 service bootanim /system/bin/bootanimation
     user graphics