xfs: set AGI buffer type in xlog_recover_clear_agi_bucket

commit 6b10b23ca94451fae153a5cc8d62fd721bec2019 upstream.

xlog_recover_clear_agi_bucket didn't set the
type to XFS_BLFT_AGI_BUF, so we got a warning during log
replay (or an ASSERT on a debug build).

    XFS (md0): Unknown buffer type 0!
    XFS (md0): _xfs_buf_ioapply: no ops on block 0xaea8802/0x1

Fix this, as was done in f19b872b for 2 other locations
with the same problem.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>