ocfs2: update seq_file index in ocfs2_dlm_seq_next

ocfs2: update seq_file index in ocfs2_dlm_seq_next

The following INFO level message was seen:

seq_file: buggy .next function ocfs2_dlm_seq_next [ocfs2] did not
update position index

Fix:
Update *pos (so m->index) to make seq_read_iter happy though the index its
self makes no sense to ocfs2_dlm_seq_next.

Link: https://lkml.kernel.org/r/20241119174500.9198-1-wen.gang.wang@oracle.com
Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>