[llvm] [X86] Support EGPR (R16-R31) for APX (PR #67702)

[Nick Desaulniers via llvm-commits]

nickdesaulniers wrote:

```
inline-asm-registers.mir, statepoint-invoke-ra-enter-at-end.mir:
The immediate (TargetInstrInfo.cpp:1612) used for the regdef/reguse is the encoding for the register
class in the enum generated by tablegen. This encoding will change
any time a new register class is added. Since the number is part
of the input, this means it can become stale.
```
yep, those changes LGTM!

https://github.com/llvm/llvm-project/pull/67702