Generated `/boot/syslinux/syslinux.cfg` is incorrect while using linux-lts kernel

If I am using Legacy BIOS + linux-lts + syslinux, it's generating incorrect `/boot/syslinux/syslinux.cfg`. 

The config file should contain: 

```
LINUX ../vmlinuz-linux-lts
INITRD ../initramfs-linux-lts.img
```

But it contains: 

```
LINUX ../vmlinuz-linux
INITRD ../initramfs-linux.img
```

And that's why system enters boot-loop without any error message. 