LU-16634 build: remove obsolete checkpatch strings

LU-16634 build: remove obsolete checkpatch strings

Remove obsolete checkpatch.pl spelling.txt warnings.  These will
not normally be hit, but the mti_flags warning is occasionally a
false positive due to a duplicate struct name (which was originally
the reason for those fields to be renamed).

Test-Parameters: trivial
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I4ee16eb62cf0ed944ac604d181ce58beead8501d
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/51596
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>