FP4: Build a disabled vbmeta image

Squashed with:
Author: Nolen Johnson <johnsonnolen@gmail.com>
Date:   Sun May 9 16:04:34 2021 -0400

    Simplify AVB flag logic

    * AVB's `--flags 3` argument builds a disabled VBMeta with
      disabled hashtree, so no need to set both flags individually.

    Change-Id: Ibe9ee322a5af58f13e76d53e18dee49451fe8838

Change-Id: Ie8f1e0929b037b35b5e45c2e31be9253fa0bb097
diff --git a/BoardConfig.mk b/BoardConfig.mk
index f9fb1ab..8c34673 100644
--- a/BoardConfig.mk
+++ b/BoardConfig.mk
@@ -201,6 +201,7 @@
 
 # Verified Boot
 BOARD_AVB_ENABLE := true
+BOARD_AVB_MAKE_VBMETA_IMAGE_ARGS += --flags 3
 BOARD_AVB_VBMETA_SYSTEM := system system_ext product
 BOARD_AVB_VBMETA_SYSTEM_KEY_PATH := external/avb/test/data/testkey_rsa2048.pem
 BOARD_AVB_VBMETA_SYSTEM_ALGORITHM := SHA256_RSA2048