[llvm] [AMDGPU] Add test to show failure with SRC_*_HI registers. NFC. (PR #154828)

[Matt Arsenault via llvm-commits]

arsenm wrote:

Really there's no reason these should have been ever defined as 64-bit constants. We only ever need the top 32-bits 

https://github.com/llvm/llvm-project/pull/154828