No longer include MirOS BSD in isolinux/syslinux boot menu

MirOS BSD no longer seems to work from isolinux/syslinux,
this might be due to:

| Since version 5.00, support for 16-bit COMBOOT modules has been dropped,
| and c32 modules switched from the COM32 object format to ELF.

as stated on http://www.syslinux.org/wiki/index.php/Comboot_API

For now it's still available in GRUB, where it's *basically*
working.