S390: Fix floating point offset calculation

During `WasmDebugBreak` we push the full 128-bit vector register
instead of only the 64-bit FP value. As a result offset calculation
must use kSimd128Size instead of kDoubleSize.

Change-Id: Icaa44d9663024b9740acbbf054f6c334ae349cf8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3487958Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Farazmand <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/main@{#79271}

src/execution/s390/frame-constants-s390.h

@@ -61,7 +61,7 @@ class WasmDebugBreakFrameConstants : public TypedFrameConstants {
       -TypedFrameConstants::kFixedFrameSizeFromFp -
       kSystemPointerSize * kNumPushedGpRegisters;
   static constexpr int kLastPushedFpRegisterOffset =
-      kLastPushedGpRegisterOffset - kDoubleSize * kNumPushedFpRegisters;
+      kLastPushedGpRegisterOffset - kSimd128Size * kNumPushedFpRegisters;
 
   // Offsets are fp-relative.
   static int GetPushedGpRegisterOffset(int reg_code) {
@@ -75,7 +75,7 @@ class WasmDebugBreakFrameConstants : public TypedFrameConstants {
     DCHECK_NE(0, kPushedFpRegs & (1 << reg_code));
     uint32_t lower_regs = kPushedFpRegs & ((uint32_t{1} << reg_code) - 1);
     return kLastPushedFpRegisterOffset +
-           base::bits::CountPopulation(lower_regs) * kDoubleSize;
+           base::bits::CountPopulation(lower_regs) * kSimd128Size;
   }
 };