can not designate the specific volume type when restore a backup to a new volume

[zhaoleilc]

Description
===========
When we restore a backup to a new volume using the command of
'cinder backup-restore --name <name> <backup>', we can not
designate the specifc volume type of the new volume. The new
volume either choose the default volume type or choose a volume
type which is filtered by some schedulers. Since the volume type
can not be designated, restore action may possibly fail.
For example, restoring a fibre channel volume backup to a
new volume of the other fibre channel volume type.

Steps to reproduce
==================
1. Create a backup for a volume.
2. Restore a new volume based on backup using the command of
'cinder backup-restore --name <name> <backup>'.
3. Inspect the type of new volume.

Expected result
===============
The new volume belongs to the specfic volume type in order
to guarantee that restore action must succeed.

Actual result
=============
The new volume may belong various kinds of volume types so
that restore action may possibly fail.

Environment
===========
The master branch of cinder.

Logs & Configs
==============
None

Implicated Codes
==============
https://opendev.org/openstack/cinder/src/branch/master/cinder/backup/api.py#L361