Set manadatory ip_version field in dhcp opts

The API is defined in:

https://github.com/openstack/neutron-lib/blob/90fa9948fd3b36d121ec5fa0b8004404f6d86b45/neutron_lib/api/definitions/extra_dhcp_opt.py#L32

We were missing the ip_version field. This was causing a bad interaction
with the OVN driver.

See: https://bugs.launchpad.net/neutron/+bug/2081161

Author: jovial

networking_mlnx/plugins/ml2/drivers/mlnx/mech_mlnx.py

@@ -86,7 +86,8 @@ def _gen_client_id_with_prefix(self, port, prefix):
     def _gen_client_id_opt(self, port):
         client_id = self._gen_client_id(port)
         return [{"opt_name": edo_ext.DHCP_OPT_CLIENT_ID,
-                 "opt_value": client_id}]
+                 "opt_value": client_id
+                 "ip_version": 4}]
 
     def _gen_none_client_id_opt(self, port):
         updated_extra_dhcp_opts = []