remove build check from ScreenLockHelper

The desired return value for this case is ambiguous, and incorrect for
the only testcase using ScreenLockHelper (builds < M running GTS should
pass this check, which requires "false" return value)

bug:30668825
Change-Id: I993854549fa979fd1eeca88382bb1bdaa56a369e
diff --git a/common/device-side/preconditions/src/com/android/compatibility/common/preconditions/ScreenLockHelper.java b/common/device-side/preconditions/src/com/android/compatibility/common/preconditions/ScreenLockHelper.java
index 385f22f..d2380af 100644
--- a/common/device-side/preconditions/src/com/android/compatibility/common/preconditions/ScreenLockHelper.java
+++ b/common/device-side/preconditions/src/com/android/compatibility/common/preconditions/ScreenLockHelper.java
@@ -18,7 +18,6 @@
 
 import android.app.KeyguardManager;
 import android.content.Context;
-import android.os.Build;
 
 /**
  * ScreenLockHelper is used to check whether the device is protected by a locked screen.
@@ -30,9 +29,6 @@
      * is no way to programmatically distinguish between the two.
      */
     public static boolean isDeviceSecure(Context context) {
-        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
-            return true; // KeyguardManager.isDeviceSecure() added in M, skip this check
-        }
         KeyguardManager km = (KeyguardManager) context.getSystemService(Context.KEYGUARD_SERVICE);
         return km.isDeviceSecure();
     }