Using secure boot status to determin its awailability for installation.

src/stage.rs

@@ -72,6 +72,10 @@ impl StageResult {
         self.add_val(val_name, ConfigValue::Bool(v))
     }
 
+    pub fn add_val_u64(self, val_name: &str, v: u64) -> Self {
+        self.add_val(val_name, ConfigValue::U64(v))
+    }
+
     pub fn get_val(&self, val_name: &str) -> Option<ConfigValue> {
         let v = self
             .config