f2fs: fix to recover inode's i_flags during POR

Testcase to reproduce this bug:
1. mkfs.f2fs /dev/sdd
2. mount -t f2fs /dev/sdd /mnt/f2fs
3. touch /mnt/f2fs/file
4. sync
5. chattr +A /mnt/f2fs/file
6. xfs_io -f /mnt/f2fs/file -c "fsync"
7. godown /mnt/f2fs
8. umount /mnt/f2fs
9. mount -t f2fs /dev/sdd /mnt/f2fs
10. lsattr /mnt/f2fs/file

-----------------N- /mnt/f2fs/file

But actually, we expect the corrct result is:

-------A---------N- /mnt/f2fs/file

The reason is we didn't recover inode.i_flags field during mount,
fix it.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/recovery.c

@@ -233,6 +233,7 @@ static void recover_inode(struct inode *inode, struct page *page)
 	inode->i_mtime.tv_nsec = le32_to_cpu(raw->i_mtime_nsec);
 
 	F2FS_I(inode)->i_advise = raw->i_advise;
+	F2FS_I(inode)->i_flags = le32_to_cpu(raw->i_flags);
 
 	recover_inline_flags(inode, raw);