[AArch64][GlobalISel] Reorder stack up-adjustment and register copies

[AArch64][GlobalISel] Reorder stack up-adjustment and register copies

This change reorders the stack up-adjustment and return value copying phases of
machine-ir generation on Aarch64. Doing so prevents a bug observed for fastcc
calls with >8 arguments, where the up-adjustment required from making that call
is placed in the wrong place relative to spill and reloading code.

See: https://github.com/llvm/llvm-project/issues/60972 for full issue
reproduction and context.

Patch contributed by Bruce Collie

Differential Revision: https://reviews.llvm.org/D144791