Btrfs: don't change inode flag of the dest clone file

The dst file will have the same inode flags with dst file after
file clone, and I think it's unexpected.

For example, the dst file will suddenly become immutable after
getting some share of data with src file, if the src is immutable.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

fs/btrfs/ioctl.c

@@ -2455,7 +2455,6 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
 			if (endoff > inode->i_size)
 				btrfs_i_size_write(inode, endoff);
 
-			BTRFS_I(inode)->flags = BTRFS_I(src)->flags;
 			ret = btrfs_update_inode(trans, root, inode);
 			BUG_ON(ret);
 			btrfs_end_transaction(trans, root);