allow init to auto-guess the correct fstab based on the ISD partition.
mount_all will then automatically load the 'correct' fstab.
We need to add this to mount_all itself (and not some new 'symlink command') as there is NO writeable tmpfs while mount_all gets executed
Revert "allow init to auto-guess the correct fstab based on the ISD partition."

This reverts commit 95f21453ea9c6c2ccd27f1ad992f6a58d62ba017.
symlink fstab
patching init to get the 'right' fstab was a bad idea as vold has the path hardcoded. This patch changes init to symlink the correct fstab to the expected place