Add admin ctxt to request qos_specs in SolidFire

We used to be able to call qos_specs_get without admin context,
however something has changed and this now fails at the object
layer in base:get_by_id.  This means that now if one uses QoS-Specs
with SolidFire and attempts to retype to another QoS Spec type,
the call will fail with no response data due to a policy/permissions
error.

It turns out that the qos_specs.py api call will let you either
pass in a context or pass in None and it implicitly gets an admin
context.  I prefer explicit behaviors, so add an explicit get admin
context in the SF driver for this call.

Change-Id: Idf10bfb8f5e738d7698233b7bdeaf45bef8914e2
Closes-Bug: #1738800

cinder/volume/drivers/solidfire.py

@@ -769,7 +769,13 @@ class SolidFireDriver(san.SanISCSIDriver):
         # and over-ride any existing
         # extra-specs settings if present
         if qos_specs_id is not None:
-            kvs = qos_specs.get_qos_specs(ctxt, qos_specs_id)['specs']
+            # Policy changes require admin context to get QoS specs
+            # at the object layer (base:get_by_id), we can either
+            # explicitly promote here, or pass in a context of None
+            # and let the qos_specs api get an admin context for us
+            # personally I prefer explicit, so here ya go.
+            admin_ctxt = context.get_admin_context()
+            kvs = qos_specs.get_qos_specs(admin_ctxt, qos_specs_id)['specs']
         else:
             kvs = specs