Correct variable usage error in test_get_hypervisor_uptime

In test_get_hypervisor_uptime, should use hyper['id'] instead
of hypers[0]['id'] in hypers loop.

Change-Id: I391ac2b6fa756fbcec8ae4fba14cf6ca248ecb5e
diff --git a/tempest/api/compute/admin/test_hypervisor.py b/tempest/api/compute/admin/test_hypervisor.py
index 55134b1..1f043dc 100644
--- a/tempest/api/compute/admin/test_hypervisor.py
+++ b/tempest/api/compute/admin/test_hypervisor.py
@@ -87,7 +87,7 @@
         ironic_only = True
         hypers_without_ironic = []
         for hyper in hypers:
-            details = (self.client.show_hypervisor(hypers[0]['id'])
+            details = (self.client.show_hypervisor(hyper['id'])
                        ['hypervisor'])
             if details['hypervisor_type'] != 'ironic':
                 hypers_without_ironic.append(hyper)