Add lights.vts module to Bullhead product packages.

For coverage demos, lights.vts needs to be built with the bullhead
target.

Test: make -j49 PRODUCT-bullhead-userdebug
Change-Id: I6a03b4c489c1e0eaafa173a252b0923694c3cc9e
diff --git a/device.mk b/device.mk
index f3b6298..7f55f92 100644
--- a/device.mk
+++ b/device.mk
@@ -183,7 +183,8 @@
     hwcomposer.msm8992 \
     libgenlock \
     memtrack.msm8992 \
-    lights.bullhead
+    lights.bullhead \
+    lights.vts
 
 PRODUCT_PACKAGES += \
     libc2dcolorconvert \