Remove unused CONF variable and import statement

This CONF vaiable and 'import config' are not necessary. So this commit
removes it.

Change-Id: I050c2c1aa8642e6a39e9dbfef63f0156d457c5fc
diff --git a/tempest/api/compute/admin/test_fixed_ips.py b/tempest/api/compute/admin/test_fixed_ips.py
index 85b03e6..ee262df 100644
--- a/tempest/api/compute/admin/test_fixed_ips.py
+++ b/tempest/api/compute/admin/test_fixed_ips.py
@@ -16,7 +16,6 @@
 #    under the License.
 
 from tempest.api.compute import base
-from tempest import config
 from tempest import exceptions
 from tempest.test import attr
 
@@ -24,8 +23,6 @@
 class FixedIPsTestJson(base.BaseComputeAdminTest):
     _interface = 'json'
 
-    CONF = config.TempestConfig()
-
     @classmethod
     def setUpClass(cls):
         super(FixedIPsTestJson, cls).setUpClass()