Add new owner to OWNERS file. am: d893eb6848 am: ad2a1bd7ad am: 7c5961bd12

Original change: https://android-review.googlesource.com/c/platform/external/avb/+/2038407

Change-Id: I75ee2f06dc61854afdfd303819766f82ab476680
diff --git a/OWNERS b/OWNERS
index 30abb1d..f9893cf 100644
--- a/OWNERS
+++ b/OWNERS
@@ -3,3 +3,4 @@
 zeuthen@google.com
 dkrahn@google.com
 tweek@google.com
+billylau@google.com