ldomctl: reject vdisk, vnet and iodevice parameters for primary domain
In analogy to guest domains requiring vcpu, memory and at least one
bootable device (vdisk, vnet or iodevice), the primary domain must not
be configured with vdisk, vnet or iodevice parameters; it does make
sense to provide virtual disks or interfaces to it and PCIe devices not
assigned to guest domains automatically end up in the primary domain.
ldom.conf(5) also documents those explicitly for guest domains only.