Call firmware wipe script during factory wipe if it exists

BUG=chrome-os-partner:2183
TEST=

Review URL: http://codereview.chromium.org/6623030

Change-Id: Iea52621a1036513f67d5e2d80eb429201c4bcdf4
diff --git a/clobber-state b/clobber-state
index 8015a22..b625224 100755
--- a/clobber-state
+++ b/clobber-state
@@ -101,6 +101,11 @@
 # Do any board specific wiping here.
 # board_factory_wipe.sh will be installed by the board overlay if necessary.
 if [ "$FACTORY_WIPE" = "factory" ]; then
+  FIRMWARE_WIPE='/usr/sbin/firmware-factory-wipe'
+  if [ -x "${FIRMWARE_WIPE}" ]; then
+    ${FIRMWARE_WIPE}
+  fi
+
   BOARD_WIPE=/usr/sbin/board_factory_wipe.sh
   if [ -x "${BOARD_WIPE}" ]; then
     ${BOARD_WIPE}