Add the ability to unlock the bootloader before doing anything else

Change-Id: I9fbd5237fc40216de5b1141219d3ab169eef0637
diff --git a/clear-factory-images-variables.sh b/clear-factory-images-variables.sh
index a92586a..2c625a7 100644
--- a/clear-factory-images-variables.sh
+++ b/clear-factory-images-variables.sh
@@ -12,12 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-unset XLOADER
-unset XLOADERSRC
 unset BOOTLOADER
 unset BOOTLOADERFILE
 unset BOOTLOADERSRC
-unset TWINBOOTLOADERS
 unset BUILD
 unset CDMARADIO
 unset DEVICE
@@ -28,4 +25,8 @@
 unset RADIOSRC
 unset SLEEPDURATION
 unset SRCPREFIX
+unset UNLOCKBOOTLOADER
 unset VERSION
+unset TWINBOOTLOADERS
+unset XLOADER
+unset XLOADERSRC