Hi all,

I'm using openstack command like this, and got error:

```

gyw@c1:~$ openstack port create --network selfservice --vnic-type remote-managed \

> --binding-profile '{"pci_vendor_info": None, "pci_slot": None, "physical_network": None, "card_serial_number": "AB0123XX0042", "pf_mac_address": "08:c0:eb:8e:bd:f8", "vf_num":1, "vnic_type": "remote-managed"}' \

> pf0vf0

Expected '<key>=<value>' or JSON data for option --binding-profile, but encountered JSON parsing error: Expecting value: line 1 column 21 (char 20)

```

So how to set "pci_vendor_info" to NoneType of python in openstack CLI's json format string?

BTW, "NoneType of python" means the NoneType in python code, like these comment in https://github.com/openstack/neutron/blob/stable/yoga/neutron/common/ovn/utils.py

```

    # With this example param_set:

    #

    # param_set = {

    #     'do_not_check_this_key': None,

    #     'pci_slot': [str],

    #     'physical_network': [str, type(None)]

    # }

    #

    # We confirm that each binding_profile key is of one of the listed types,

    # allowing validation of polymorphic entries.

    #

    # 'physical_network' is polymorphic because:  When a VNIC_REMOTE_MANAGED or

    # VNIC_DIRECT with PORT_CAP_SWITCHDEV capability port is attached to a

    # project network backed by an overlay (tunneled) network the value will be

    # 'None'.  For the case of ports attached to a project network backed by

    # VLAN the value will be of type ``str``.  This comes from Nova and is

    # provided in the ``physical_network`` tag in the Nova PCI Passthrough

    # configuration.

    #

    # In the above example the type of the value behind 'do_not_check_this_key'

    # will not be checked, 'pci_slot' must be ``str``, 'physical_network  must

    # be either ``str`` or ``NoneType``.

```

Thank you~