cros_bundle_firmware: Add missing GBB flags

These can be set in the dts to change the image behavior.
It's particularly useful for testing.

BUG=none
TEST=Add gbb-flag-force-dev-boot-legacy to cros/dts/factory-friendly.dtsi
     and see that the default GBB flags are 0xb9 instead of 0x39
BRANCH=link

Change-Id: I504bd1f3b27a864798278a724c4ad467189ab81d
Reviewed-on: https://gerrit.chromium.org/gerrit/34791
Commit-Ready: Stefan Reinauer <reinauer@chromium.org>
Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
Tested-by: Stefan Reinauer <reinauer@chromium.org>
diff --git a/host/lib/bundle_firmware.py b/host/lib/bundle_firmware.py
index d94f506..6f37c51 100644
--- a/host/lib/bundle_firmware.py
+++ b/host/lib/bundle_firmware.py
@@ -254,6 +254,8 @@
         'gbb-flag-force-dev-switch-on': 0x00000008,
         'gbb-flag-force-dev-boot-usb': 0x00000010,
         'gbb-flag-disable-fw-rollback-check': 0x00000020,
+        'gbb-flag-enter-triggers-tonorm': 0x00000040,
+        'gbb-flag-force-dev-boot-legacy': 0x00000080,
     }
     gbb_flags = 0
     for flag_name, flag_value in flag_properties.items():