Update physical LEDs as part of Lamp test

- Add the getSubTreePaths method for utils and update all physical
  LEDs.

- Uses GetSubTreePath on Physical LED paths and interfaces and
  updates all the LEDs to ON as part of start or restart of the test.

- When the lamp test is stopped or the timer expires, all the LEDs
  are turned OFF.

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I27727db62fe963a1a7c8b391d73801bcaf9efeec
diff --git a/led-main.cpp b/led-main.cpp
index 7857e91..c1e1a67 100644
--- a/led-main.cpp
+++ b/led-main.cpp
@@ -48,7 +48,7 @@
     groups.emplace_back(std::make_unique<phosphor::led::Group>(
         bus, LAMP_TEST_OBJECT, manager, serialize,
         std::bind(std::mem_fn(&phosphor::led::LampTest::requestHandler),
-                  &lampTest, std::placeholders::_1)));
+                  &lampTest, std::placeholders::_1, std::placeholders::_2)));
 #endif
 
     /** Now create so many dbus objects as there are groups */