Fix target_vendor for aarch64-nintendo-switch-freestanding

Previously set to `target_vendor = "unknown"`, but Nintendo is clearly
the vendor of the Switch, and is also reflected in the target name
itself.

compiler/rustc_target/src/spec/targets/aarch64_nintendo_switch_freestanding.rs

@@ -23,6 +23,7 @@ pub(crate) fn target() -> Target {
             linker: Some("rust-lld".into()),
             link_script: Some(LINKER_SCRIPT.into()),
             os: "horizon".into(),
+            vendor: "nintendo".into(),
             max_atomic_width: Some(128),
             stack_probes: StackProbeType::Inline,
             panic_strategy: PanicStrategy::Abort,