[RISCV] Use XLenVT as LocVT for f16/f32/f164 with Zfinx in CC_RISCV_FastCC.

This is need to make sure we create FMV_X_W/FMV_X_H/bitcast nodes
that match up with what return lowering will do.

Author: topperc

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -19150,6 +19150,8 @@ bool RISCV::CC_RISCV_FastCC(const DataLayout &DL, RISCVABI::ABI ABI,
       (LocVT == MVT::f64 && Subtarget.is64Bit() &&
        Subtarget.hasStdExtZdinx())) {
     if (MCRegister Reg = State.AllocateReg(getFastCCArgGPRs(ABI))) {
+      LocInfo = CCValAssign::BCvt;
+      LocVT = Subtarget.getXLenVT();
       State.addLoc(CCValAssign::getReg(ValNo, ValVT, Reg, LocVT, LocInfo));
       return false;
     }