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/utils.cpp b/utils.cpp
index 6c122f9..116f0c3 100644
--- a/utils.cpp
+++ b/utils.cpp
@@ -114,4 +114,4 @@
 
 } // namespace utils
 } // namespace led
-} // namespace phosphor
\ No newline at end of file
+} // namespace phosphor