Bug fix SignificantMotion test activity.

Do a null check on mScreenManipulator before trying to turn off the screen. It may be set to null
if there is no SMD sensor on the device.

Bug: 24055225
Change-Id: I71d8215f9b45318f501b15eafbccb3d5873d6402
diff --git a/apps/CtsVerifier/src/com/android/cts/verifier/sensors/SignificantMotionTestActivity.java b/apps/CtsVerifier/src/com/android/cts/verifier/sensors/SignificantMotionTestActivity.java
index 6dbf8cc..2dfc7c8 100644
--- a/apps/CtsVerifier/src/com/android/cts/verifier/sensors/SignificantMotionTestActivity.java
+++ b/apps/CtsVerifier/src/com/android/cts/verifier/sensors/SignificantMotionTestActivity.java
@@ -287,7 +287,9 @@
 
     @Override
     protected void activityCleanUp() {
-        mScreenManipulator.turnScreenOff();
+        if (mScreenManipulator != null) {
+            mScreenManipulator.turnScreenOff();
+        }
         LocalBroadcastManager.getInstance(this).unregisterReceiver(myBroadCastReceiver);
     }