AsmParser: Stop requiring 'name:' when it's not printed

r230877 optimized which fields are written out for `CHECK`-ability, but
apparently missed changing some of them to optional in `LLParser`.

Fixes PR22921.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232400 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed