Stabilize sse4a and tbm target features

 - remove some stabilized target features from `gate.rs`

Author: sayantn

core/src/lib.rs

@@ -200,8 +200,6 @@
 #![feature(riscv_target_feature)]
 #![feature(rtm_target_feature)]
 #![feature(s390x_target_feature)]
-#![feature(sse4a_target_feature)]
-#![feature(tbm_target_feature)]
 #![feature(wasm_target_feature)]
 #![feature(x86_amx_intrinsics)]
 // tidy-alphabetical-end

stdarch/crates/core_arch/src/lib.rs

@@ -18,8 +18,6 @@
     rustc_attrs,
     staged_api,
     doc_cfg,
-    tbm_target_feature,
-    sse4a_target_feature,
     riscv_target_feature,
     arm_target_feature,
     mips_target_feature,