cros_bundle_firmware: Disable bootsecure for the flasher

We cannot use this mode with the flasher since it needs to be able to
specify the command line to process.

BUG=chrome-os-partner:21115
TEST=manual
crosfw -b peach_pit -VSF

See that the flasher runs correctly and Pit then boots.

Change-Id: I6a562661c839f3266b946f8da0e12af3ace77e3c
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/62747
Reviewed-by: Chirantan Ekbote <ekbotec@chromium.org>
diff --git a/host/lib/write_firmware.py b/host/lib/write_firmware.py
index a8c3182..5312da6 100644
--- a/host/lib/write_firmware.py
+++ b/host/lib/write_firmware.py
@@ -870,6 +870,7 @@
            port number of servo to use.
   """
   write = WriteFirmware(tools, fdt, output, bundle, update, verify)
+  fdt.PutInteger('/config', 'bootsecure', 0)
   write.SelectServo(servo)
   if flash_dest:
     write.text_base = bundle.CalcTextBase('flasher ', fdt, flasher)