This reverts commit c96bd78e.

So our code is one big mess and we modify domain definition while
building qemu_command line and our hotplug code share only part
of the parsing and command line building code.  Let's revert
that change because to fix it properly would require refactor and
move a lot of things.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1430275