docs: remove obsolete links in the xfs online repair documentation

Online repair is now merged in upstream, no need to point to patchset
links anymore.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Author: Darrick J. Wong