[openwrt/openwrt] realtek: Makefile: add rt-loader-standalone and zynsig recipes

[LEDE Commits]

hauke pushed a commit to openwrt/openwrt.git, branch main:
https://git.openwrt.org/1c63273d8d935c4ab432df70cce6b79d90934a54

commit 1c63273d8d935c4ab432df70cce6b79d90934a54
Author: Andreas Böhler <dev at aboehler.at>
AuthorDate: Sun Oct 12 19:33:19 2025 +0200

    realtek: Makefile: add rt-loader-standalone and zynsig recipes
    
    This adds the build recipes for rt-loader-standalone and zynsig to the
    Makefile. The recipes are required for the upcoming ZyXEL GS1920 series.
    
    Signed-off-by: Andreas Böhler <dev at aboehler.at>
    Link: https://github.com/openwrt/openwrt/pull/20439
    Signed-off-by: Hauke Mehrtens <hauke at hauke-m.de>
---
 target/linux/realtek/image/Makefile | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/target/linux/realtek/image/Makefile b/target/linux/realtek/image/Makefile
index db1776340e..1ff4201bc6 100644
--- a/target/linux/realtek/image/Makefile
+++ b/target/linux/realtek/image/Makefile
@@ -37,6 +37,12 @@ define Build/rt-loader-no-uimage
         mv "$@.new" "$@"
 endef
 
+define Build/rt-loader-standalone
+	$(MAKE) all clean -C rt-loader CROSS_COMPILE="$(TARGET_CROSS)" \
+		FLASH_ADDR=$(FLASH_ADDR) KERNEL_IMG_OUT="$@.new" BUILD_DIR="$@.build"
+	mv "$@.new" "$@"
+endef
+
 define Build/zyxel-vers
        ( echo VERS;\
        for hw in $(ZYXEL_VERS); do\
@@ -102,6 +108,12 @@ define Build/linksys-image
 	mv $@.new $@
 endef
 
+define Build/zynsig
+	$(STAGING_DIR_HOST)/bin/zynsig -i $@ \
+		-o $@.new
+	mv $@.new $@
+endef
+
 define Device/Default
   PROFILES = Default
   KERNEL := \