e2fsck: clear badblocks inode when checksum fails

e2fsck: clear badblocks inode when checksum fails

If the badblocks inode fails checksum verification, just clear the
inode and move on.  If we don't do this, we can end up importing a lot
of garbage into the badblocks list, which will then cause fsck to try
to regenerate anything that was sitting atop the supposedly damaged
blocks.  Given that most hardware will remap bad sectors transparently
from ext4, the number of people this could affect adversely is pretty
low.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>