plugins: provider: Use CallsOrigin instead of derived types for GListStore

Otherwise we run into trouble when using `g_list_store_find()`

plugins/mm/calls-mm-provider.c

@@ -433,7 +433,7 @@ static void
 calls_mm_provider_init (CallsMMProvider *self)
 {
   self->status = g_strdup (_("Initialised"));
-  self->origins = g_list_store_new (CALLS_TYPE_MM_ORIGIN);
+  self->origins = g_list_store_new (CALLS_TYPE_ORIGIN);
 }