vold no longer does MS_MOVE; remove tmpfs.

MS_MOVE was used when staging external storage devices, which no
longer occurs.  In fact, having a writable tmpfs was masking a vold
bug around moving apps to SD cards.

Bug: 11175082
Change-Id: Ib2d7561c3a0b6fde94f651a496cb0c1f12f88d96

rootdir/init.rc

@@ -66,8 +66,6 @@ loglevel 3
 
     # Directory for putting things only root should see.
     mkdir /mnt/secure 0700 root root
-    # Create private mountpoint so we can MS_MOVE from staging
-    mount tmpfs tmpfs /mnt/secure mode=0700,uid=0,gid=0
 
     # Directory for staging bindmounts
     mkdir /mnt/secure/staging 0700 root root
@@ -143,7 +141,6 @@ on post-fs
     mount rootfs rootfs / ro remount
     # mount shared so changes propagate into child namespaces
     mount rootfs rootfs / shared rec
-    mount tmpfs tmpfs /mnt/secure private rec
 
     # We chown/chmod /cache again so because mount is run as root + defaults
     chown system cache /cache