include/image.mk: fix missing right parenthesis (#21766)

Signed-off-by: Felix Fietkau <[email protected]>

SVN-Revision: 48609

include/image.mk

@@ -187,7 +187,8 @@ ifneq ($(CONFIG_NAND_SUPPORT),)
 	[ -z "$(3)" ] || $(CP) "$(3)" "$(KDIR_TMP)/sysupgrade-$(1)/kernel"
 	(cd "$(KDIR_TMP)"; $(TAR) cvf \
 		"$(BIN_DIR)/$(IMG_PREFIX)-$(1)-$(2)-sysupgrade.tar" sysupgrade-$(1) \
-			$(if $(SOURCE_DATE_EPOCH),--mtime="@$(SOURCE_DATE_EPOCH)")
+			$(if $(SOURCE_DATE_EPOCH),--mtime="@$(SOURCE_DATE_EPOCH)") \
+	)
    endef
 
 # $(1) board name