Fix the get property (#55745) (#55788)

* Fix the get property (#55745)

(cherry picked from commit c7bf3e035b)

changelogs/fragments/55745-azure_rm_common.yaml

@@ -0,0 +1,2 @@
+bugfixes:
+  - Fix cannot get credential when `source_auth` set to `credential_file`.

lib/ansible/module_utils/azure_rm_common.py

@@ -1226,7 +1226,7 @@ class AzureRMAuth(object):
 
         if auth_source == 'credential_file':
             self.log("Retrieving credentials from credential file")
-            profile = params.get('profile', 'default')
+            profile = params.get('profile') or 'default'
             default_credentials = self._get_profile(profile)
             return default_credentials