Android 8.1 仅支持PIN码的锁屏方式

最近收到客户需求，要求设备仅支持PIN码的锁屏方式，具体修改参照如下：

/vendor/mediatek/proprietary/packages/apps/MtkSettings/src/com/android/settings/password/ChooseLockGeneric.java

            // Used for testing purposesfindPreference(ScreenLockType.NONE.preferenceKey).setViewId(R.id.lock_none);findPreference(KEY_SKIP_FINGERPRINT).setViewId(R.id.lock_none);findPreference(ScreenLockType.PIN.preferenceKey).setViewId(R.id.lock_pin);findPreference(ScreenLockType.PASSWORD.preferenceKey).setViewId(R.id.lock_password);
+            removePreference(ScreenLockType.PATTERN.preferenceKey);
+            removePreference(ScreenLockType.PASSWORD.preferenceKey);

重新编译验证，修改生效，设备的锁屏方式已改为仅支持PIN码