ubifs: use generic_fillattr()

	struct ubifs_inode *ui = ubifs_inode(inode);

	mutex_lock(&ui->ui_mutex);

	stat->dev = inode->i_sb->s_dev;

	stat->ino = inode->i_ino;

	stat->mode = inode->i_mode;

	stat->nlink = inode->i_nlink;

	stat->uid = inode->i_uid;

	stat->gid = inode->i_gid;

	stat->rdev = inode->i_rdev;

	stat->atime = inode->i_atime;

	stat->mtime = inode->i_mtime;

	stat->ctime = inode->i_ctime;

	generic_fillattr(inode, stat);

	stat->blksize = UBIFS_BLOCK_SIZE;

	stat->size = ui->ui_size;