fix defconfig usage

mk/kernel-build.mk

@@ -72,7 +72,7 @@ $(LINUX_DIR)/.config: $(LINUX_DIR)/.prepared
 	$(START_TRACE) "target/$(ADK_TARGET_ARCH)-kernel-configure.. "
 	echo "-${KERNEL_RELEASE}" >${LINUX_DIR}/localversion
 ifeq ($(ADK_TARGET_LINUX_KERNEL_USE_DEFCONFIG),y)
-	${KERNEL_MAKE_ENV} $(MAKE) -C "${LINUX_DIR}" ${KERNEL_MAKE_OPTS} $(ADK_TARGET_KERNEL_DEFCONFIG) $(MAKE_TRACE)
+	${KERNEL_MAKE_ENV} $(MAKE) -C "${LINUX_DIR}" ${KERNEL_MAKE_OPTS} $(ADK_TARGET_LINUX_KERNEL_DEFCONFIG) $(MAKE_TRACE)
 else ifeq ($(ADK_TARGET_LINUX_KERNEL_USE_CUSTOMCONFIG),y)
 	@if [ ! -f $(ADK_TOPDIR)/$(ADK_TARGET_LINUX_KERNEL_CUSTOMCONFIG_PATH) ];then \
 		echo "no kernel configuration found in $(ADK_TOPDIR)/$(ADK_TARGET_LINUX_KERNEL_CUSTOMCONFIG_PATH)"; \