Revert "vold: Handle wrong entries in vold.fstab"

This reverts commit 3cb59fa4a1a5af6f1006dc00c6ceb2c2ddc9ceae.
Revert "Allow symlinks to be used in vold.fstab"

This reverts commit d4d5f3dd55ca635859b38f31e8df5d2c709c20da.