Look for product configs in device/ in addition to vendor/

This will allow to create open-sourceable product configurations.

Change-Id: I4e73347c2095935340bfc8c3737c2adf1ef22a9c
diff --git a/core/product.mk b/core/product.mk
index a9a24d2..5417242 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -23,7 +23,8 @@
 # $(call ) isn't necessary.
 #
 define _find-android-products-files
-$(shell test -d vendor && find vendor -maxdepth 6 -name AndroidProducts.mk) \
+$(shell test -d device && find device -maxdepth 6 -name AndroidProducts.mk) \
+  $(shell test -d vendor && find vendor -maxdepth 6 -name AndroidProducts.mk) \
   $(SRC_TARGET_DIR)/product/AndroidProducts.mk
 endef