Fix in eos get_config cliconf api (ansible#38682)

If format is passed as None to get_config api, wrong command is
genereted ie. `show running-configuration | None | section interface`.
Add format type in command only if format value is either not `text`
or  `None`.

lib/ansible/plugins/cliconf/eos.py

@@ -51,13 +51,12 @@ def get_config(self, source='running', format='text', flags=None):
         lookup = {'running': 'running-config', 'startup': 'startup-config'}
         if source not in lookup:
             return self.invalid_params("fetching configuration from %s is not supported" % source)
-        if format == 'text':
-            cmd = b'show %s ' % lookup[source]
-        else:
-            cmd = b'show %s | %s' % (lookup[source], format)
 
-        flags = [] if flags is None else flags
-        cmd += ' '.join(flags)
+        cmd = b'show %s ' % lookup[source]
+        if format and format is not 'text':
+            cmd += b'| %s ' % format
+
+        cmd += ' '.join(to_list(flags))
         cmd = cmd.strip()
         return self.send_command(cmd)