xfs: set remote symlink buffer type for recovery

The logging of a remote symlink block does not set the buffer type
being logged, and hence on recovery the type of buffer is not
recognised and hence CRCs are not calculated after replay. This
results in log recoery throwing:

XFS (vdc): Unknown buffer type 0

errors, and subsequent reads of the symlink failing CRC
verification. Found via fsstress + godown.

Reported by: Michael L. Semon <mlsemon35@gmail.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>