manta: start mobicore daemon

Set the ownership/perms for /dev/mobicore

Change-Id: I44538f0c43b641ec0c071bb12082d7d076005a76
diff --git a/ueventd.manta.rc b/ueventd.manta.rc
index c69dad0..ea92d97 100644
--- a/ueventd.manta.rc
+++ b/ueventd.manta.rc
@@ -90,3 +90,6 @@
 
 #JPEG
 /dev/video12              0660   media      media
+
+# mobicore DRM
+/dev/mobicore             0660   drmrpc     drmrpc