Don't reset static sp<TunerClient> JTuner::mTunerClient in ~JTuner()

Bug: 197167400
Test: atest TunerTest#testClose
Change-Id: If9ac8cf4a528bce928a0691970f7a33d21ef2e17

media/jni/android_media_tv_Tuner.cpp

@@ -1203,7 +1203,6 @@ JTuner::~JTuner() {
 
     env->DeleteWeakGlobalRef(mObject);
     env->DeleteGlobalRef(mClass);
-    mTunerClient = nullptr;
     mFeClient = nullptr;
     mDemuxClient = nullptr;
     mClass = nullptr;