xfs: ensure we copy buffer type in da btree root splits

When splitting the root of the da btree, we shuffled data between
buffers and the structures that track them. At one point, we copy
data and state from one buffer to another, including the ops
associated with the buffer. When we do this, we also need to copy
the buffer type associated with the buf log item so that the buffer
is logged correctly. If we don't do that, log recovery won't
recognise it and hence it won't recalculate the CRC on the buffer
after recovery. This leads to a directory block that can't be read
after recovery has run.

Found by inspection after finding the same problem with remote
symlink buffers.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>