Fix tempest.conf generation

[service_available] is not being generated. This patch fixes it.

Change-Id: I364621ce96a1d2f6bc49df6f2868b093f719a6f5
Closes-Bug: #1613542
diff --git a/ironic_tempest_plugin/config.py b/ironic_tempest_plugin/config.py
index 9802934..7b09e90 100644
--- a/ironic_tempest_plugin/config.py
+++ b/ironic_tempest_plugin/config.py
@@ -14,6 +14,15 @@
 
 from tempest import config  # noqa
 
+service_available_group = cfg.OptGroup(name="service_available",
+                                       title="Available OpenStack Services")
+
+ServiceAvailableGroup = [
+    cfg.BoolOpt("ironic-inspector",
+                default=True,
+                help="Whether or not ironic-inspector is expected to be"
+                " available"),
+]
 
 baremetal_introspection_group = cfg.OptGroup(
     name="baremetal_introspection",