mediatek: remove no longer needed sysupgrade hack

Keeping configuration is now handled in fstools like for other types
of flash as well.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

target/linux/mediatek/mt7622/base-files/lib/preinit/79_move_config

@@ -1,18 +0,0 @@
-. /lib/upgrade/common.sh
-
-RECOVERY_PART=/dev/mmcblk0p6
-
-move_config() {
-	if [ -b $RECOVERY_PART ]; then
-		insmod nls_cp437
-		insmod nls_iso8859-1
-		insmod fat
-		insmod vfat
-		mkdir -p /recovery
-		mount -o rw,noatime $RECOVERY_PART /recovery
-		[ -f "/recovery/$BACKUP_FILE" ] && mv -f "/recovery/$BACKUP_FILE" /
-		umount /recovery
-	fi
-}
-
-boot_hook_add preinit_mount_root move_config