[][OpenWrt Dev][Add missing uboot-envtool config file for mt7981 sysupgrade]

[Description]
Add missing uboot-envtool config file for mt7981 sysupgrade

[Release-log]
N/A

Change-Id: If589b7bbeab0f352253a7cc986a5b4e4d2f6b757
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6187509
diff --git a/target/linux/mediatek/mt7981/base-files/lib/upgrade/platform.sh b/target/linux/mediatek/mt7981/base-files/lib/upgrade/platform.sh
index 29f970f..6eb1e5f 100644
--- a/target/linux/mediatek/mt7981/base-files/lib/upgrade/platform.sh
+++ b/target/linux/mediatek/mt7981/base-files/lib/upgrade/platform.sh
@@ -1,4 +1,5 @@
 RAMFS_COPY_BIN='mkfs.f2fs blkid blockdev fw_printenv fw_setenv'
+RAMFS_COPY_DATA="/etc/fw_env.config /var/lock/fw_printenv.lock"
 platform_do_upgrade() {
 	local board=$(board_name)