ScaleIO: Enable multiattach for volumes

Enable the multiattach capability to allow volumes
to be attached to more than one instance

Change-Id: I1db2771f7c970341f62271a857795d413a506a34

cinder/volume/drivers/dell_emc/scaleio/driver.py

@@ -986,6 +986,7 @@ class ScaleIODriver(driver.VolumeDriver):
         stats['consistent_group_snapshot_enabled'] = True
         stats['thick_provisioning_support'] = True
         stats['thin_provisioning_support'] = True
+        stats['multiattach'] = True
         pools = []
 
         free_capacity = 0
@@ -1054,6 +1055,7 @@ class ScaleIODriver(driver.VolumeDriver):
                     'reserved_percentage': 0,
                     'thin_provisioning_support': True,
                     'thick_provisioning_support': True,
+                    'multiattach': True,
                     'provisioned_capacity_gb': provisioned_capacity,
                     'max_over_subscription_ratio':
                         self.configuration.max_over_subscription_ratio

releasenotes/notes/scaleio-enable-multiattach-e7d84ffa282842e9.yaml

@@ -0,0 +1,9 @@
+---
+features:
+  - |
+    The multiattach capability has been enabled and verified
+    as working with the ScaleIO driver. It is the users’
+    responsibility to add some type of exclusion (at the file
+    system or network file system layer) to prevent multiple
+    writers from corrupting data on the volume.
+