Rollup merge of rust-lang#135015 - heiher:stabilize-loongarch-target-features, r=Amanieu

Partially stabilize LoongArch target features

Stabilization PR for the LoongArch target features. This PR stabilizes some of the target features tracked by rust-lang#44839.

Specifically, this PR stabilizes the following target features:

* f
* d
* frecipe
* lasx
* lbt
* lsx
* lvz

Docs PR: rust-lang/reference#1707

r? `@Amanieu`

Author: jhpratt

compiler/rustc_target/src/target_features.rs

@@ -693,17 +693,17 @@ static CSKY_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
 
 static LOONGARCH_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     // tidy-alphabetical-start
-    ("d", Unstable(sym::loongarch_target_feature), &["f"]),
+    ("d", Stable, &["f"]),
     ("div32", Unstable(sym::loongarch_target_feature), &[]),
-    ("f", Unstable(sym::loongarch_target_feature), &[]),
-    ("frecipe", Unstable(sym::loongarch_target_feature), &[]),
+    ("f", Stable, &[]),
+    ("frecipe", Stable, &[]),
     ("lam-bh", Unstable(sym::loongarch_target_feature), &[]),
     ("lamcas", Unstable(sym::loongarch_target_feature), &[]),
-    ("lasx", Unstable(sym::loongarch_target_feature), &["lsx"]),
-    ("lbt", Unstable(sym::loongarch_target_feature), &[]),
+    ("lasx", Stable, &["lsx"]),
+    ("lbt", Stable, &[]),
     ("ld-seq-sa", Unstable(sym::loongarch_target_feature), &[]),
-    ("lsx", Unstable(sym::loongarch_target_feature), &["d"]),
-    ("lvz", Unstable(sym::loongarch_target_feature), &[]),
+    ("lsx", Stable, &["d"]),
+    ("lvz", Stable, &[]),
     ("relax", Unstable(sym::loongarch_target_feature), &[]),
     ("scq", Unstable(sym::loongarch_target_feature), &[]),
     ("ual", Unstable(sym::loongarch_target_feature), &[]),