Add option to allow filtering by mac-address on port list

yanxa@ubuntu:python-openstackclient$ openstack port list --help
usage: openstack port list [-h] [-f {csv,json,table,value,yaml}] [-c COLUMN]
                           [--max-width <integer>] [--noindent]
                           [--quote {all,minimal,none,nonnumeric}]
                           [--device-owner <device-owner>]
                           [--network <network>]
                           [--router <router> | --server <server>] [--long]

List ports

optional arguments:
  -h, --help show this help message and exit
  --device-owner <device-owner>
                        List only ports with the specified device owner. This
                        is the entity that uses the port (for example,
                        network:dhcp).
  --network <network> List only ports connected to this network (name or ID)
  --router <router> List only ports attached to this router (name or ID)
  --server <server> List only ports attached to this server (name or ID)
  --long List additional fields in output

yanxa@ubuntu:python-openstackclient$ openstack port list
+--------------------------------------+------+-------------------+-----------------------------------------------+--------+
| ID | Name | MAC Address | Fixed IP Addresses | Status |
+--------------------------------------+------+-------------------+-----------------------------------------------+--------+
| 00b61d62-7efd-40db-9f67-df53b3756b60 | | fa:16:3e:cc:43:67 | ip_address='10.0.0.1', subnet_id='e82a77a0 | DOWN |
| | | | -3b6c-4b4b-b047-125b225fc8a2' | |
| 5a1b9e14-ee68-4aa9-a72f-039e2cb8341e | | fa:16:3e:26:a8:39 | ip_address='172.24.4.3', subnet_id='6600978a- | DOWN |
| | | | 193c-4c6e-84dc-b259d812ab1e' | |
| | | | ip_address='2001:db8::c', | |
| | | | subnet_id='8b1e8469-7765-40bc- | |
| | | | b48d-e79085403467' | |
| 6e57a4e6-3021-4300-8130-d2623c7824cc | | fa:16:3e:1c:df:d9 | ip_address='10.0.0.2', subnet_id='e82a77a0 | DOWN |
| | | | -3b6c-4b4b-b047-125b225fc8a2' | |
| | | | ip_address='2001:db8:8000:0:f816:3eff:fe1c:df | |
| | | | d9', subnet_id='550e7ced-48fe- | |
| | | | 42b8-b4f6-9ccdae901266' | |
| cba034bc-62ab-4275-9500-8bf2b54f2c95 | | fa:16:3e:33:3c:3c | ip_address='2001:db8:8000::1', subnet_id | DOWN |
| | | | ='550e7ced-48fe-42b8-b4f6-9ccdae901266' | |
+--------------------------------------+------+-------------------+-----------------------------------------------+--------+

If the port number is large scale, it spend too many time via "os port list |grep xx:xx:xx:xx:xx:xx", and "grep" can not give all fields of a port.

We may import the "--mac-address" option.