Revert "Make keystore a core service"

This reverts commit 7fd8e853e96f7b223d3744c84a68acc74f57657f.

Test: still see keystore process running
Bug: 112038744
Bug: 150267620
Change-Id: I4fe3c6aeecf960377671d11be0a4dc9fa60dfb18
diff --git a/keystore/keystore.rc b/keystore/keystore.rc
index a688c5f..132039a 100644
--- a/keystore/keystore.rc
+++ b/keystore/keystore.rc
@@ -1,5 +1,5 @@
 service keystore /system/bin/keystore /data/misc/keystore
-    class core
+    class main
     user keystore
     group keystore drmrpc readproc log
     writepid /dev/cpuset/foreground/tasks