[ARM64] Debug info for structure argument missing DW_AT_location

Summary:
Prevent eliminating dbg_val due to COPY.

Fixes this
https://bugs.llvm.org/show_bug.cgi?id=40709

Patch by: Kamlesh Kumar (kamleshbhalui)

Reviewers: aprantl, dblaikie, vsk, dsanders

Reviewed By: dsanders

Subscribers: dstenb, kristof.beyls, hiraditya, llvm-commits

Tags: #debug-info, #llvm

Differential Revision: https://reviews.llvm.org/D73159