spufs: convert spufs_context_open() to FD_PREPARE()

static int spufs_context_open(const struct path *path)

{

	int ret;

	struct file *filp;

	ret = get_unused_fd_flags(0);

	if (ret < 0)

		return ret;

	filp = dentry_open(path, O_RDONLY, current_cred());

	if (IS_ERR(filp)) {

		put_unused_fd(ret);

		return PTR_ERR(filp);

	}

	filp->f_op = &spufs_context_fops;

	fd_install(ret, filp);

	return ret;

	FD_PREPARE(fdf, 0, dentry_open(path, O_RDONLY, current_cred()));

	if (fdf.err)

		return fdf.err;

	fd_prepare_file(fdf)->f_op = &spufs_context_fops;

	return fd_publish(fdf);

}

static struct spu_context *