Description of problem:
Create a volume as multi-attach is failed with "No valid host was found. No weighed hosts available" using Netapp back-end   

Version-Release number of selected component (if applicable):
python-cinder-7.0.1-5.el7ost.noarch
openstack-cinder-7.0.1-5.el7ost.noarch
python-cinderclient-1.4.0-1.el7ost.noarch

How reproducible:
100%

Steps to Reproduce:
1. Configure Netapp as back-end
2. Create a multi-attach volume 
   

Actual results:
Creating a multi-attach volume is failed

Expected results:
Creating a multi-attach volume should succeed 

Additional info:

[stack@instack ~]$ cinder create 1 --allow-multiattach --volume-type netapp1


[stack@instack ~]$ cinder show de99494c-8e5c-440a-83cc-ed43fd2a43a5
+---------------------------------------+--------------------------------------+
|                Property               |                Value                 |
+---------------------------------------+--------------------------------------+
|              attachments              |                  []                  |
|           availability_zone           |                 nova                 |
|                bootable               |                false                 |
|          consistencygroup_id          |                 None                 |
|               created_at              |      2016-02-14T07:50:03.000000      |
|              description              |                 None                 |
|               encrypted               |                False                 |
|                   id                  | de99494c-8e5c-440a-83cc-ed43fd2a43a5 |
|                metadata               |                  {}                  |
|            migration_status           |                 None                 |
|              multiattach              |                 True                 |
|                  name                 |                 None                 |
|         os-vol-host-attr:host         |                 None                 |
|     os-vol-mig-status-attr:migstat    |                 None                 |
|     os-vol-mig-status-attr:name_id    |                 None                 |
|      os-vol-tenant-attr:tenant_id     |   3a85e4a722e64171be1f495f3c47ccc8   |
|   os-volume-replication:driver_data   |                 None                 |
| os-volume-replication:extended_status |                 None                 |
|           replication_status          |               disabled               |
|                  size                 |                  1                   |
|              snapshot_id              |                 None                 |
|              source_volid             |                 None                 |
|                 status                |                error                 |
|                user_id                |   895a2cab60e449939bc1764458f305a3   |
|              volume_type              |               netapp1                |
+---------------------------------------+--------------------------------------+

From scheduler log:

2016-02-11 09:45:43.669 2798 ERROR cinder.scheduler.flows.create_volume [req-cdd32b70-dc44-4d78-8b71-dbfb201ba3ae 895a2cab60e449939bc1764458f305a3 3a85e4a722e64171be1f495f3c47ccc8 - - -] Failed to run task cinder.scheduler.flows.create_volume.ScheduleCreateVolumeTask;volume:create: No valid host was found. No weighed hosts available
2016-02-11 09:45:43.670 2798 DEBUG cinder.volume.flows.common [req-cdd32b70-dc44-4d78-8b71-dbfb201ba3ae 895a2cab60e449939bc1764458f305a3 3a85e4a722e64171be1f495f3c47ccc8 - - -] Updating volume: 2cd7a5e4-d8a6-49b7-92db-8ae15cd744e2 with {'status': 'error'} due to: No valid host was found. No weighed hosts available _update_object /usr/lib/python2.7/site-packages/cinder/volume/flows/common.py:87