libbinder_ndk: simplify AStatus get

There is no need for a mutable version of this function, and the const
version can return a reference (it never returns null).

Bug: 167686803
Test: atest CtsNdkBinderTestCases
Change-Id: I1c8fb89632c0d6ac921a81dfbb8a797f737db64c
diff --git a/libs/binder/ndk/status_internal.h b/libs/binder/ndk/status_internal.h
index f6227f7..cb96e48 100644
--- a/libs/binder/ndk/status_internal.h
+++ b/libs/binder/ndk/status_internal.h
@@ -25,8 +25,7 @@
     AStatus() {}  // ok
     explicit AStatus(::android::binder::Status&& status) : mStatus(std::move(status)) {}
 
-    ::android::binder::Status* get() { return &mStatus; }
-    const ::android::binder::Status* get() const { return &mStatus; }
+    const ::android::binder::Status& get() const { return mStatus; }
 
    private:
     ::android::binder::Status mStatus;