[llvm] [AArch64][GISel] Assign registers into FPR if they feed into FP instructions indirectly via PHI (PR #94618)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

```
%4:gpr(s32) = G_PHI %1(s32), %bb.1, %11(s32), %bb.2

%29:fpr(s32) = COPY %4(s32)
%26:gpr(s32) = G_FCMP floatpred(ogt), %9(s32), %29
```
`%4` is used by a floating operation (G_FCMP)?!?

https://github.com/llvm/llvm-project/pull/94618