fs/ocfs2: fix comments mentioning i_mutex

fs/ocfs2: fix comments mentioning i_mutex

inode->i_mutex has been replaced with inode->i_rwsem long ago.  Fix
comments still mentioning i_mutex.

Link: https://lkml.kernel.org/r/20220214031314.100094-1-hongnan.li@linux.alibaba.com
Signed-off-by: hongnanli <hongnan.li@linux.alibaba.com>
Acked-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: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>