remove rva23s64 from riscv64a23-unknown-linux-gnu target

Author: ZhongyaoChen

compiler/rustc_target/src/spec/targets/riscv64a23_unknown_linux_gnu.rs

@@ -17,7 +17,7 @@ pub(crate) fn target() -> Target {
         options: TargetOptions {
             code_model: Some(CodeModel::Medium),
             cpu: "generic-rv64".into(),
-            features: "+rva23u64,+rva23s64".into(),
+            features: "+rva23u64".into(),
             llvm_abiname: "lp64d".into(),
             max_atomic_width: Some(64),
             supported_split_debuginfo: Cow::Borrowed(&[SplitDebuginfo::Off]),

src/doc/rustc/src/platform-support/riscv64a23-unknown-linux-gnu.md

@@ -3,7 +3,7 @@
 **Tier: 3**
 
 RISC-V target using the ratified [RVA23 Profile](https://github.com/riscv/riscv-profiles/blob/main/src/rva23-profile.adoc).
-This target will enable all mandary features of rva23u64 and rva23s64 by default.
+This target will enable all mandary features of rva23u64 by default.
 
 ## Target maintainers