[llvm] [AMDGPU] Make max dwords of memory cluster configurable (PR #119342)

[via llvm-commits]

ruiling wrote:

> function attribute

Thanks! What's the suggested way to access that value in function attribute from the SIInstrInfo? Maybe keep a record of that value in MachineFunctionInfo and get from it?

https://github.com/llvm/llvm-project/pull/119342