ext4: fix lockdep warning when enabling MMP

When we enable MMP in ext4_multi_mount_protect() during mount or
remount, we end up calling sb_start_write() from write_mmp_block(). This
triggers lockdep warning because freeze protection ranks above s_umount
semaphore we are holding during mount / remount. The problem is harmless
because we are guaranteed the filesystem is not frozen during mount /
remount but still let's fix the warning by not grabbing freeze
protection from ext4_multi_mount_protect().

Cc: stable@kernel.org
Reported-by:  <syzbot+6b7df7d5506b32467149@syzkaller.appspotmail.com>
Link: https://syzkaller.appspot.com/bug?id=ab7e5b6f400b7778d46f01841422e5718fb81843


Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230411121019.21940-1-jack@suse.cz


Signed-off-by: Theodore Ts'o <tytso@mit.edu>