##### SUMMARY
If a host has port set to a usermacro, the host is created successfully. On the next run, the update fails with `ValueError: invalid literal for int() with base 10: {$MACRO}`.

Tested with the latest `zabbix_host` from git.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
zabbix_host

##### ANSIBLE VERSION
latest

##### CONFIGURATION
Not relevant.

##### OS / ENVIRONMENT
Not relevant.

##### STEPS TO REPRODUCE
Have a host definition with usermacro used for port in an interface. Create the host via Ansible, then run the playbook again.

##### EXPECTED RESULTS
Success (reported as no change).

##### ACTUAL RESULTS

```paste below
Traceback (most recent call last):
  File \"/home/ansible/.ansible/tmp/ansible-tmp-1571042967.61-236562069605480/AnsiballZ_zabbix_host.py\", line 114, in <module>
    _ansiballz_main()
  File \"/home/ansible/.ansible/tmp/ansible-tmp-1571042967.61-236562069605480/AnsiballZ_zabbix_host.py\", line 106, in _ansiballz_main
    invoke_module(zipped_mod, temp_path, ANSIBALLZ_PARAMS)
  File \"/home/ansible/.ansible/tmp/ansible-tmp-1571042967.61-236562069605480/AnsiballZ_zabbix_host.py\", line 49, in invoke_module
    imp.load_module(__main__, mod, module, MOD_DESC)
  File \"/tmp/ansible_zabbix_host_payload_7ml4r2/__main__.py\", line 857, in <module>
  File \"/tmp/ansible_zabbix_host_payload_7ml4r2/__main__.py\", line 817, in main
  File \"/tmp/ansible_zabbix_host_payload_7ml4r2/__main__.py\", line 479, in check_all_properties
  File \"/tmp/ansible_zabbix_host_payload_7ml4r2/__main__.py\", line 437, in check_interface_properties
ValueError: invalid literal for int() with base 10: {$MACRO}
```

- For more information, review host interface documentation at
            - U(https://www.zabbix.com/documentation/4.0/manual/api/reference/hostinterface/object)
        suboptions:
            type:
                description:
                    - Interface type to add
                    - Numerical values are also accepted for interface type
                    - 1 = agent
                    - 2 = snmp
                    - 3 = ipmi
                    - 4 = jmx
                choices: ['agent', 'snmp', 'ipmi', 'jmx']
                required: true
            main:
                type: int
                description:
                    - Whether the interface is used as default.
                    - If multiple interfaces with the same type are provided, only one can be default.
                    - 0 (not default), 1 (default)
                default: 0
                choices: [0, 1]
            useip:
                type: int
                description:
                    - Connect to host interface with IP address instead of DNS name.
                    - 0 (don't use ip), 1 (use ip)
                default: 0
                choices: [0, 1]
            ip:
                type: str