[][OpenWrt Dev][Mark image slot valid for mmc dual-boot upgrading]

[Description]
Add support for mmc dual-boot upgrading to mark image slot just updated valid

[Release-log]
N/A

Change-Id: I082175d2598d37a7462c5562815eacb175a3e390
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6105789
diff --git a/target/linux/mediatek/base-files/lib/upgrade/mmc.sh b/target/linux/mediatek/base-files/lib/upgrade/mmc.sh
index d975e4a..fee9091 100644
--- a/target/linux/mediatek/base-files/lib/upgrade/mmc.sh
+++ b/target/linux/mediatek/base-files/lib/upgrade/mmc.sh
@@ -169,6 +169,7 @@
 		mkdir -p /var/lock
 		touch /var/lock/fw_printenv.lock
 		fw_setenv "dual_boot.current_slot" "${upgrade_image_slot}"
+		fw_setenv "dual_boot.slot_${upgrade_image_slot}_invalid" "0"
 	}
 
 	rootfs_data_dev=$(cat /sys/module/boot_param/parameters/rootfs_data_part 2>/dev/null)