Revert "s390x: [baseline] enable sparkplug on s390x"

This reverts commit 78bc7852.

Reason for revert: revert due to failure on native tests.

Original change's description:
> s390x: [baseline] enable sparkplug on s390x
>
> Change-Id: I4646bb0f3f6291c97bb4b397d6248b9bdaa2059a
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3439641
> Reviewed-by: Victor Gomes <victorgomes@chromium.org>
> Commit-Queue: Junliang Yan <junyan@redhat.com>
> Cr-Commit-Position: refs/heads/main@{#78959}

Change-Id: I8d006211e42ace4db804f1a88f2749282ef2de32
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3440771
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78985}

src/flags/flag-definitions.h

@@ -197,7 +197,7 @@ struct MaybeBoolFlag {
 
 #if V8_TARGET_ARCH_IA32 || V8_TARGET_ARCH_X64 || V8_TARGET_ARCH_ARM64 ||     \
     V8_TARGET_ARCH_ARM || V8_TARGET_ARCH_RISCV64 || V8_TARGET_ARCH_MIPS64 || \
-    V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_LOONG64 || V8_TARGET_ARCH_S390X
+    V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_LOONG64
 #define ENABLE_SPARKPLUG true
 #else
 // TODO(v8:11421): Enable Sparkplug for other architectures