bundle_firmware: Add enable-serial to gbb_flag_properties

BUG=chromium:210230
BRANCH=None
TEST=Add gbb-flag-enable-serial to jerry fmap.dts. Verify flag is set on
the emerge-veyron_jerry chromeos-bootimage.

Change-Id: I68e773118bee5a3c74d4c8832e5f1daf1d1a4f76
Signed-off-by: Mary Ruthven <mruthven@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/312830
Reviewed-by: Simon Glass <sjg@chromium.org>
1 file changed