xfsprogs: kill experimental warnings for v5 filesystems

xfsprogs: kill experimental warnings for v5 filesystems

With xfsprogs now being close to feature complete on v5 filesystems,
remove the experimental warnings from the superblock verifier. This
means that we don't need to filter such warnings from the output in
xfstests and so we can see exactly what tests are failing due to
code deficiencies rather than from detecting warning noise.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Rich Johnston <rjohnston@sgi.com>