module_utils/ansible_ipa_replica: Initialize skip_schema_check to None

This setting can not be set for replica deployments, but needs to be
initilized.

roles/ipareplica/module_utils/ansible_ipa_replica.py

@@ -204,6 +204,7 @@ class installer_obj(object):
         self.unattended = not self.interactive
         #self.promote = self.replica_file is None
         self.promote = True
+        self.skip_schema_check = None
 
     #def __getattribute__(self, attr):
     #    value = super(installer_obj, self).__getattribute__(attr)