[llvm] [BOLT][AArch64] Tweak heuristics for epilogue recognition (PR #169584)

[Paschalis Mpeis via llvm-commits]

https://github.com/paschalis-mpeis commented:

Thanks YongKang. The tuned/simplified heuristic is to allow more cases?
ie previously this was rejected
```armasm
  ldr x30, [sp], #0x10
  mov x0, x1
  br x3
```

Just wondering, have you seen cases where this leads to more CFGs being generated?

nit: could maybe drop "As commented in the code," from commit message?

https://github.com/llvm/llvm-project/pull/169584