mod_image_for_factor: never touch firmware for factory test images

we don't want any possibility for firmware to be changed in factory setup

BUG=none
TEST=build_image; image_to_usb --factory

Change-Id: Ibef767ea621193afb7fbca5ea96120a506891dcb

R=nsanders@chromium.org

Review URL: http://codereview.chromium.org/6764010
diff --git a/mod_for_factory_scripts/200patchInitScript b/mod_for_factory_scripts/200patchInitScript
index cbe29bc..5812b63 100755
--- a/mod_for_factory_scripts/200patchInitScript
+++ b/mod_for_factory_scripts/200patchInitScript
@@ -7,6 +7,7 @@
 echo "Applying patch to init scripts."
 
 touch "${ROOT_FS_DIR}/root/.factory_test"
+touch "${ROOT_FS_DIR}/root/.leave_firmware_alone"
 
 patch -d "${ROOT_FS_DIR}" -Np1 <<EOF
 --- old/etc/init/ui.conf	2010-04-28 21:28:38.886069000 -0700