Define the payload key on PRODUCT_IOT builds.
am: 78850aa56f

Change-Id: I3a96c58082d57c32454a75195ecd2aab90e68e36
diff --git a/Android.mk b/Android.mk
index 4801a49..226b09f 100644
--- a/Android.mk
+++ b/Android.mk
@@ -1013,7 +1013,7 @@
 
 # Update payload signing public key.
 # ========================================================
-ifdef BRILLO
+ifeq ($(PRODUCT_IOT),true)
 include $(CLEAR_VARS)
 LOCAL_MODULE := brillo-update-payload-key
 LOCAL_MODULE_CLASS := ETC
@@ -1022,7 +1022,7 @@
 LOCAL_SRC_FILES := update_payload_key/brillo-update-payload-key.pub.pem
 LOCAL_BUILT_MODULE_STEM := update_payload_key/brillo-update-payload-key.pub.pem
 include $(BUILD_PREBUILT)
-endif  # BRILLO
+endif  # PRODUCT_IOT
 
 # Brillo update payload generation script
 # ========================================================