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##### SUMMARY
<!--- Explain the problem briefly below -->
Fix iosxr interfaces zuul failure, which is failing coz of lowercase `loopback` instead of `Loopback` in iosxr. (ref: https://logs.zuul.ansible.com/03/61303/28b181fe1fcb3831516b336923ce39e29942ee50/third-party-check/ansible-test-network-integration-iosxr-python27/80fc31b/controller/ara-report/reports/01641385-035c-4e22-a0bd-fdfbf67a8cb9.html)
##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
iosxr_interfaces
##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
devel
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below

```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->
zuul

##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml

```

<!--- HINT: You can paste gist.github.com links for larger files -->

##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->
iosxr_interfaces should pass as expected

##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->
iosxr_interfaces fails
<!--- Paste verbatim command output between quotes -->
```paste below

```

""" Populate the facts for interfaces
        :param module: the module instance
        :param connection: the device connection
        :param data: previously collected conf
        :rtype: dictionary
        :returns: facts
        """
        objs = []
        if not data:
            data = connection.get('show running-config interface')
        
        config = data.split('interface ')
        for conf in config:
            if conf:
                obj = self.render_config(self.generated_spec, conf)
                if obj:
                    objs.append(obj)
        facts = {}
        if objs:
            facts['interfaces'] = []
            params = utils.validate_config(self.argument_spec, {'config': objs})
            for cfg in params['config']:
                facts['interfaces'].append(utils.remove_empties(cfg))
        ansible_facts['ansible_network_resources'].update(facts)
        return ansible_facts
    def render_config(self, spec, conf):