[llvm] [AMDGPU] Fix computeKnownBitsForTargetNode for AMDGPUISD::LDS (PR #210350)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> I don't know how to write a more targeted test for this.

ptrtoint + and which can be eliminated based on the number of bits?

https://github.com/llvm/llvm-project/pull/210350