PPC/s390: [wasm-simd] Move i64x2.widen_i32x4_{s,u} to mvp and remove ifdefs

Port ec8fbed7

Original Commit Message:

    These instructions were accepted into the proposal:
    https://github.com/WebAssembly/simd/pull/290

R=zhin@chromium.org, joransiu@ca.ibm.com, junyan@redhat.com, midawson@redhat.com
BUG=
LOG=N

Change-Id: I69bbe90ab3af30d7748332a7e99b7812c95f96b4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2644939Reviewed-by: Junliang Yan <junyan@redhat.com>
Reviewed-by: Milad Fa <mfarazma@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#72257}

src/compiler/backend/ppc/instruction-selector-ppc.cc

@@ -2259,6 +2259,10 @@ void InstructionSelector::VisitInt64AbsWithOverflow(Node* node) {
   V(F32x4Trunc)             \
   V(F32x4NearestInt)        \
   V(I64x2Neg)               \
+  V(I64x2SConvertI32x4Low)  \
+  V(I64x2SConvertI32x4High) \
+  V(I64x2UConvertI32x4Low)  \
+  V(I64x2UConvertI32x4High) \
   V(I32x4Neg)               \
   V(I32x4Abs)               \
   V(I32x4SConvertF32x4)     \

src/compiler/backend/s390/instruction-selector-s390.cc

@@ -2515,14 +2515,18 @@ void InstructionSelector::VisitWord64AtomicStore(Node* node) {
   V(F32x4Trunc)             \
   V(F32x4NearestInt)        \
   V(I64x2Neg)               \
-  V(I16x8Abs)               \
+  V(I64x2SConvertI32x4Low)  \
+  V(I64x2SConvertI32x4High) \
+  V(I64x2UConvertI32x4Low)  \
+  V(I64x2UConvertI32x4High) \
   V(I32x4Neg)               \
+  V(I32x4Abs)               \
   V(I32x4SConvertI16x8Low)  \
   V(I32x4SConvertI16x8High) \
   V(I32x4UConvertI16x8Low)  \
   V(I32x4UConvertI16x8High) \
-  V(I32x4Abs)               \
   V(I16x8Neg)               \
+  V(I16x8Abs)               \
   V(I16x8SConvertI8x16Low)  \
   V(I16x8SConvertI8x16High) \
   V(I16x8UConvertI8x16Low)  \