uboot-mediatek: fix mt7622 rfb1 build

Add back the default LK image header to generate u-boot-mtk.bin. This
is the default behavior before u-boot v2022.01. If "u-boot-mtk.bin"
doesn't boot, please try "u-boot.bin" and report it.

Signed-off-by: Shiji Yang <yangshiji66@outlook.com>

package/boot/uboot-mediatek/patches/408-arm-mediatek-add-back-mt7622-LK-image-header.patch

@@ -0,0 +1,24 @@
+From 1845b514511398cc0ba219a47958f078a2f7f67d Mon Sep 17 00:00:00 2001
+From: Shiji Yang <yangshiji66@outlook.com>
+Date: Tue, 8 Jul 2025 19:50:53 +0800
+Subject: [PATCH] arm: mediatek: add back mt7622 LK image header
+
+The LK image header was lost since commit df3ab898f644
+("arm: mediatek: merge board Kconfigs into mach-mediatek").
+
+Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
+---
+ arch/arm/mach-mediatek/Kconfig | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/arch/arm/mach-mediatek/Kconfig
++++ b/arch/arm/mach-mediatek/Kconfig
+@@ -158,7 +158,7 @@ config MTK_BROM_HEADER_INFO
+ 	string
+ 	default "media=nor" if TARGET_MT8518 || TARGET_MT8512 || TARGET_MT7629
+ 	default "media=emmc" if TARGET_MT8516 || TARGET_MT8365 || TARGET_MT8183
+-	default "lk=1" if TARGET_MT7623
++	default "lk=1" if TARGET_MT7622 || TARGET_MT7623
+ 
+ config MTK_TZ_MOVABLE
+ 	select ARCH_MISC_INIT