include/image.mk: allow passing a compat string to the NAND image template

Signed-off-by: John Crispin <john@phrozen.org>

include/image.mk

@@ -210,14 +210,15 @@ endef
 # $(1): board name
 # $(2): rootfs type
 # $(3): kernel image
+# $(4): compat string
 ifneq ($(CONFIG_NAND_SUPPORT),)
    define Image/Build/SysupgradeNAND
-	mkdir -p "$(KDIR_TMP)/sysupgrade-$(1)/"
-	echo "BOARD=$(1)" > "$(KDIR_TMP)/sysupgrade-$(1)/CONTROL"
-	[ -z "$(2)" ] || $(CP) "$(KDIR)/root.$(2)" "$(KDIR_TMP)/sysupgrade-$(1)/root"
-	[ -z "$(3)" ] || $(CP) "$(3)" "$(KDIR_TMP)/sysupgrade-$(1)/kernel"
+	mkdir -p "$(KDIR_TMP)/sysupgrade-$(if $(4),$(4),$(1))/"
+	echo "BOARD=$(if $(4),$(4),$(1))" > "$(KDIR_TMP)/sysupgrade-$(if $(4),$(4),$(1))/CONTROL"
+	[ -z "$(2)" ] || $(CP) "$(KDIR)/root.$(2)" "$(KDIR_TMP)/sysupgrade-$(if $(4),$(4),$(1))/root"
+	[ -z "$(3)" ] || $(CP) "$(3)" "$(KDIR_TMP)/sysupgrade-$(if $(4),$(4),$(1))/kernel"
 	(cd "$(KDIR_TMP)"; $(TAR) cvf \
-		"$(BIN_DIR)/$(IMG_PREFIX)-$(1)-$(2)-sysupgrade.tar" sysupgrade-$(1) \
+		"$(BIN_DIR)/$(IMG_PREFIX)-$(1)-$(2)-sysupgrade.tar" sysupgrade-$(if $(4),$(4),$(1)) \
 			$(if $(SOURCE_DATE_EPOCH),--mtime="@$(SOURCE_DATE_EPOCH)") \
 	)
    endef