xfs: inode scrubber shouldn't bother with raw checks

The inode scrubber tries to _iget the inode prior to running checks.
If that _iget call fails with corruption errors that's an automatic
fail, regardless of whether it was the inode buffer read verifier,
the ifork verifier, or the ifork formatter that errored out.

Therefore, get rid of the raw mode scrub code because it's not needed.
Found by trying to fix some test failures in xfs/379 and xfs/415.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>