LU-8066 lfsck: use underscores in lfsck status files

LU-8066 lfsck: use underscores in lfsck status files

Use underscores to separate words in the lfsck_layout
and oi_scrub files instead of hyphens, to match the use
in lfsck_namespace and consistency with other files.

Test-Parameters: trivial testlist=sanity-lfsck,sanity-scrub
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I5306d82a4e6056a5098d1753f53cb4ee4e2540e5
Reviewed-on: https://review.whamcloud.com/36715
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Olaf Faaland-LLNL <faaland1@llnl.gov>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>