fpi-ssm: Clear delayed actions for parent and child on subssm start

While timeout was already cleared for parent, we didn't properly delete the
cancellable.

Although we'd warn anyways when starting the SSM, is still better to clear
any delayed action also for the sub-SSM

libfprint/fpi-ssm.c

@@ -338,7 +338,10 @@ fpi_ssm_start_subsm (FpiSsm *parent, FpiSsm *child)
 {
   BUG_ON (parent->timeout);
   child->parentsm = parent;
-  g_clear_pointer (&parent->timeout, g_source_destroy);
+
+  fpi_ssm_clear_delayed_action (parent);
+  fpi_ssm_clear_delayed_action (child);
+
   fpi_ssm_start (child, __subsm_complete);
 }