[llvm] [Codegen] [DebugInfo] use the getDwarfRegNum() defined in MCRegisterInfo.h instead of defining a new one (PR #97157)

[Chen Zheng via llvm-commits]

https://github.com/chenzheng1030 commented:

Thanks very much for addressing this issue.

After adding super and sub register handling in `getDwarfRegNum`, can we remove the `DwarfRegAlias` in the td files?

https://github.com/llvm/llvm-project/pull/97157