[hip] Fix ambiguity from `>>>` of CUDA.

Summary:
- For template arguments ending with `>>>`, we should cease lookahead
  and treat it as type-id firstly, so that deduction could work
  properly.

Reviewers: tra, yaxunl

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D61396

llvm-svn: 360214