Revert "Auto merge of #98333 - SimonSapin:riscv-atomic, r=Amanieu"

This reverts commit 90f0b24, reversing
changes made to e173a8e.

Author: taiki-e

compiler/rustc_target/src/spec/riscv32i_unknown_none_elf.rs

@@ -11,7 +11,7 @@ pub fn target() -> Target {
             linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
             linker: Some("rust-lld".into()),
             cpu: "generic-rv32".into(),
-            max_atomic_width: Some(32),
+            max_atomic_width: Some(0),
             atomic_cas: false,
             panic_strategy: PanicStrategy::Abort,
             relocation_model: RelocModel::Static,

compiler/rustc_target/src/spec/riscv32im_unknown_none_elf.rs

@@ -11,7 +11,7 @@ pub fn target() -> Target {
             linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
             linker: Some("rust-lld".into()),
             cpu: "generic-rv32".into(),
-            max_atomic_width: Some(32),
+            max_atomic_width: Some(0),
             atomic_cas: false,
             features: "+m".into(),
             panic_strategy: PanicStrategy::Abort,

compiler/rustc_target/src/spec/riscv32imc_unknown_none_elf.rs

@@ -11,7 +11,7 @@ pub fn target() -> Target {
             linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
             linker: Some("rust-lld".into()),
             cpu: "generic-rv32".into(),
-            max_atomic_width: Some(32),
+            max_atomic_width: Some(0),
             atomic_cas: false,
             features: "+m,+c".into(),
             panic_strategy: PanicStrategy::Abort,