Add the restoreLedsAssert method for LED manager

- Logically, Since the physical LEDs states should not be operated
  during the lamp test, all the physical LEDs states before and
  during the lamp test should be saved and restored after the lamp
  test.

Tested:
- Store the state of all the physical LEDs before the lamp test,
  and keep the state of all the physical LEDs consistent after
  the lamp test.

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I8b321bae2e38001ea33a80bda8badcf4c8a55040
diff --git a/led-main.cpp b/led-main.cpp
index c1e1a67..df057a5 100644
--- a/led-main.cpp
+++ b/led-main.cpp
@@ -49,6 +49,12 @@
         bus, LAMP_TEST_OBJECT, manager, serialize,
         std::bind(std::mem_fn(&phosphor::led::LampTest::requestHandler),
                   &lampTest, std::placeholders::_1, std::placeholders::_2)));
+
+    // Register a lamp test method in the manager class, and call this method
+    // when the lamp test is started
+    manager.setLampTestCallBack(
+        std::bind(std::mem_fn(&phosphor::led::LampTest::processLEDUpdates),
+                  &lampTest, std::placeholders::_1, std::placeholders::_2));
 #endif
 
     /** Now create so many dbus objects as there are groups */