s390: fix kernel install

target/s390/Makefile

@@ -47,11 +47,8 @@ endif
 endif
 
 # image creation and kernel install
-kernel-strip:
-	$(TARGET_CROSS)objcopy $(OSTRIP) -S $(KERNEL) $(BUILD_DIR)/$(TARGET_KERNEL)
-
-kernel-install: kernel-strip
-	@cp $(BUILD_DIR)/$(TARGET_KERNEL) $(FW_DIR)/${TARGET_KERNEL}
+kernel-install:
+	@cp $(KERNEL) $(FW_DIR)/${TARGET_KERNEL}
 
 # filesystem specific targets
 ifeq ($(ADK_TARGET_FS),archive)