Make ScanResult final.

While normally this would be a breaking API change, since we never
actually exposed a constructor for this class it's safe to mark it as
final.

Bug: 149912516
Test: Builds
Change-Id: I5555a17d98ebe8c61064ef64e508f707aff4eeb7
diff --git a/wifi/api/system-current.txt b/wifi/api/system-current.txt
index 150a650..e39e148 100644
--- a/wifi/api/system-current.txt
+++ b/wifi/api/system-current.txt
@@ -208,7 +208,7 @@
     field @Deprecated public byte id;
   }
 
-  public class ScanResult implements android.os.Parcelable {
+  public final class ScanResult implements android.os.Parcelable {
     field public static final int CIPHER_CCMP = 3; // 0x3
     field public static final int CIPHER_GCMP_256 = 4; // 0x4
     field public static final int CIPHER_NONE = 0; // 0x0