Use real capabilites for volume type instead of fake ones

Replace fake capabilities requirements in volume type extra spec
with real capabilites that Cinder/iSCSI driver would report.

fix bug: 1098017

Change-Id: I0e226c14df95097cfdf653f0a13a45b8acff39da
diff --git a/tempest/tests/volume/admin/test_volume_types.py b/tempest/tests/volume/admin/test_volume_types.py
index 8ebb78f..65c975a 100644
--- a/tempest/tests/volume/admin/test_volume_types.py
+++ b/tempest/tests/volume/admin/test_volume_types.py
@@ -126,7 +126,8 @@
         try:
             body = {}
             name = rand_name("volume-type-")
-            extra_specs = {"Spec1": "Val1", "Spec2": "Val2"}
+            extra_specs = {"storage_protocol": "iSCSI",
+                           "vendor_name": "Open Source"}
             resp, body = self.client.\
             create_volume_type(name, extra_specs=extra_specs)
             self.assertEqual(200, resp.status)