Avoid null pointer dereference.  Pointed out by Nick Hudson; variant on his diff from NetBSD.
Avoid null pointer dereference.  Pointed out by Nick Hudson; variant on his
diff from NetBSD.

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars