[Settings] Convert to getSystemService(Class<T>)

Change to getSystemService(Class<T>) to align the capability with framework
part.

Bug: 179640862
Test: local
Change-Id: I1b4812044fc4876bec6645570049a60f9470dbbd

src/com/android/settings/wifi/details2/WifiPrivacyPreferenceController2.java

@@ -45,7 +45,7 @@ public class WifiPrivacyPreferenceController2 extends BasePreferenceController i
     public WifiPrivacyPreferenceController2(Context context) {
         super(context, KEY_WIFI_PRIVACY);
 
-        mWifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
+        mWifiManager = context.getSystemService(WifiManager.class);
     }
 
     public void setWifiEntry(WifiEntry wifiEntry) {