move enterprise specific code to separate method "_update_context_error_message_for_enterprise"

lms/djangoapps/student_account/views.py

@@ -381,6 +381,15 @@ def _third_party_auth_context(request, redirect_to, tpa_hint=None):
                 context['errorMessage'] = _(unicode(msg))  # pylint: disable=translation-of-non-string
                 break
 
+        context = _update_context_for_enterprise_error_message(context, enterprise_customer)
+
+    return context
+
+
+def _update_context_for_enterprise_error_message(context, enterprise_customer=None):
+    """
+    Return updated context with modified `errorMessage` for enterprise.
+    """
     if enterprise_customer and context['errorMessage']:
         context['errorMessage'] = Text(_(
             u'We are sorry, you are not authorized to access {platform_name} via this channel. '