mke2fs: prevent creation of filesystem with unsupported revision

mke2fs: prevent creation of filesystem with unsupported revision

It's a bit strange to accept revision levels higher than
the code creating the filesystem can understand, so don't
allow it.

At least the kernel will mount the fs readonly if it's too
high, but no other utility will touch it, so you can't
fix the error.

Just reject anything > EXT2_MAX_SUPP_REV at mkfs time.

Signed-off-by: Frank Sorenson <fsorenso@redhat.com>
[sandeen@redhat.com: Add more verbose commit log]
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>