PPC: Fix LoadSimd128 to used the passed scratch register

Change-Id: Id9a8f9d7a7ccf7dc85a140ed3da30f429fc073ba
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2587008Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#71723}

src/codegen/ppc/macro-assembler-ppc.cc

@@ -2957,7 +2957,7 @@ void TurboAssembler::LoadSimd128(Simd128Register dst, const MemOperand& mem,
       sp, sp,
       Operand(base::bits::WhichPowerOfTwo(16)));  // equivalent to &= -16
   addi(sp, sp, Operand(-16));
-  stxvd(kScratchDoubleReg, MemOperand(r0, sp));
+  stxvd(ScratchDoubleReg, MemOperand(r0, sp));
   // Load it with correct lane ordering.
   lvx(dst, MemOperand(r0, sp));
   mr(sp, ScratchReg);