Revert "storaged: assign to system-background cpuset"

This reverts commit e1d4b072ff5045cfb72f915b161281be512c1e3c.

Change-Id: I6be0af0e85efff672ea95e9a05c33618cd994dd5
diff --git a/storaged/storaged.rc b/storaged/storaged.rc
index a8fa5a7..5fdbb8a 100644
--- a/storaged/storaged.rc
+++ b/storaged/storaged.rc
@@ -2,4 +2,3 @@
     class main
     file /d/mmc0/mmc0:0001/ext_csd r
     group root readproc
-    writepid /dev/cpuset/system-background/tasks