audit: Use 'mark' name for fsnotify_mark variables

Variables pointing to fsnotify_mark are sometimes called 'entry' and
sometimes 'mark'. Use 'mark' in all places.

Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
[PM: minor merge fuzz due to updated patches previously in the series]
Signed-off-by: Paul Moore <paul@paul-moore.com>