Run fastboot oem unlock before flashing

Change-Id: I395bc0ce77bab5a80af9e49ac0815ab23b679eba
diff --git a/factory-images/generate-factory-images-package.sh b/factory-images/generate-factory-images-package.sh
index 4a341f5..91f552c 100755
--- a/factory-images/generate-factory-images-package.sh
+++ b/factory-images/generate-factory-images-package.sh
@@ -44,5 +44,6 @@
 BOOTLOADERFILE=bootloader.bin
 BOOTLOADER=4.13
 SLEEPDURATION=10
+UNLOCKBOOTLOADER=true
 ERASEALL=true
 source ../../../common/generate-factory-images-common.sh