build: Fix kernelsavedefconfig target

Change-Id: Ie3d9a187693f2435f2555658c833de666848e48e
diff --git a/build/tasks/kernel.mk b/build/tasks/kernel.mk
index 490e0db..64fcc20 100644
--- a/build/tasks/kernel.mk
+++ b/build/tasks/kernel.mk
@@ -442,9 +442,7 @@
 .PHONY: kernelsavedefconfig alldefconfig
 
 kernelsavedefconfig: $(KERNEL_OUT)
-	$(call make-kernel-target,$(KERNEL_DEFCONFIG))
-	env KCONFIG_NOTIMESTAMP=true \
-		 $(call make-kernel-target,savedefconfig)
+	$(call make-kernel-config,$(KERNEL_OUT),$(KERNEL_DEFCONFIG))
 	cp $(KERNEL_OUT)/defconfig $(KERNEL_DEFCONFIG_SRC)
 
 alldefconfig: $(KERNEL_OUT)