CodeReview for MdePkg/BaseMemoryXXX libraries. Refine file description, function comments and move some redundant logic.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@6167 6f19259b-4bc3-4df7-8a09-765794883524

MdePkg/Library/BaseMemoryLibOptPei/ZeroMemWrapper.c

@@ -50,9 +50,6 @@ ZeroMem (
 {
   ASSERT (!(Buffer == NULL && Length > 0));
   ASSERT (Length <= (MAX_ADDRESS - (UINTN)Buffer + 1));
-  if (Length == 0) {
-  	return Buffer;
-  }  
   
   return InternalMemZeroMem (Buffer, Length);
 }