[llvm] Adding new reg bank select rules for G_AMDGPU_SPONENTRY (PR #200864)

[Chinmay Deshpande via llvm-commits]

https://github.com/chinmaydd approved this pull request.

LGTM.

Could you update the title to include the AMDGPU/GISel prefix ? Also, fix it to say that we are adding RegBankLegalize rules instead. Thanks

https://github.com/llvm/llvm-project/pull/200864