Cleanup some leftover macros

Change-Id: I0efdbb9cdfef6c206201adf4d75a0c542979d2f3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3640267Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Deepti Gandluri <gdeepti@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80480}

src/compiler/backend/instruction-selector.cc

@@ -2830,11 +2830,6 @@ void InstructionSelector::VisitI16x8RelaxedQ15MulRS(Node* node) {
 }
 #endif  // !V8_TARGET_ARCH_ARM64
 
-#if !V8_TARGET_ARCH_X64 && !V8_TARGET_ARCH_IA32 && !V8_TARGET_ARCH_ARM64 && \
-    !V8_TARGET_ARCH_RISCV64
-#endif  // !V8_TARGET_ARCH_X64 && !V8_TARGET_ARCH_IA32 && !V8_TARGET_ARCH_ARM64
-        // && !V8_TARGET_ARCH_RISCV64
-
 void InstructionSelector::VisitFinishRegion(Node* node) { EmitIdentity(node); }
 
 void InstructionSelector::VisitParameter(Node* node) {