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/config.mk b/core/config.mk
index f35b44e..64a5dd0 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -122,6 +122,7 @@
 board_config_mk := \
 	$(strip $(wildcard \
 		$(SRC_TARGET_DIR)/board/$(TARGET_DEVICE)/BoardConfig.mk \
+		device/*/$(TARGET_DEVICE)/BoardConfig.mk \
 		vendor/*/$(TARGET_DEVICE)/BoardConfig.mk \
 	))
 ifeq ($(board_config_mk),)