[MIRPraser] Improve error checking for typed immediate operands

Summary:
This improves error checks for typed immediate operands introduced in
D45948 (rL331586), and removes a code block copied by mistake.

Reviewers: rtereshin

Subscribers: dschuff, sbc100, jgravelle-google, llvm-commits

Differential Revision: https://reviews.llvm.org/D46491

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@331600 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed