DebugInfo: Convert DW_OP_piece => DW_OP_bit_piece

r228631 stopped using `DW_OP_piece` inside `DIExpression`s in the IR,
but it apparently missed updating these testcases.  Caught by verifier
checks for `MDExpression` while working on moving the new hierarchy into
place.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230882 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed