Revert "fsck.cramfs: Fix bus error on broken file system."

Revert "fsck.cramfs: Fix bus error on broken file system."

This reverts commit 7cb962c77015e9383b53eeb22ce732cb5216bbc3.

It can't be right that we mmap (start + super.size) bytes from a file
which is usually only super.size bytes large. The patch "fixed" a
problem when super.size is bad but now it fails for the correct case:

$ mkdir -p root/subdir
$ ./mkfs.cramfs -p root cramfs
$ ./fsck.cramfs cramfs
Bus error (core dumped)

We will fix the original problem later.

CC: Tobias Stoeckmann <tobias@stoeckmann.org>
Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>