Fix the comments to follow UEFI Spec regarding how to check an EFI_HANDLE is valid/invalid.

Signed-off-by: niruiyu
Reviewed-by: lgao4

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11981 6f19259b-4bc3-4df7-8a09-765794883524
3 files changed