1. Support get default value for ref opcode logic. 2. Correct the sample for ref opcode with default value. 3. Refine logic about processing device path info in ref value. Signed-off-by: ydong10 Reviewed-by: lgao4 git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12774 6f19259b-4bc3-4df7-8a09-765794883524