ext4: switch to fscrypt_prepare_lookup()

	struct inode *inode;

	struct ext4_dir_entry_2 *de;

	struct buffer_head *bh;

	int err;

	if (ext4_encrypted_inode(dir)) {

		int res = fscrypt_get_encryption_info(dir);

		/*

		 * DCACHE_ENCRYPTED_WITH_KEY is set if the dentry is

		 * created while the directory was encrypted and we

		 * have access to the key.

		 */

		if (fscrypt_has_encryption_key(dir))

			fscrypt_set_encrypted_dentry(dentry);

		fscrypt_set_d_op(dentry);

		if (res && res != -ENOKEY)

			return ERR_PTR(res);

	}

	err = fscrypt_prepare_lookup(dir, dentry, flags);

	if (err)

		return ERR_PTR(err);

	if (dentry->d_name.len > EXT4_NAME_LEN)

		return ERR_PTR(-ENAMETOOLONG);