LU-6142 obd: change lmd flags to bitmap

LU-6142 obd: change lmd flags to bitmap

Change lmd flags to an enum that is accessible with the Linux
bitmap API. This lays the foundation for creating a match table
for the server options for mounting.

Change-Id: If7906a9a3ba177b67d0cfbaa276a00a6ba9b7b6d
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/49912
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>