There are a few extra exceptions that weren't being accounted for when
creating the alias for a controller. This resulted in 1) incorrect
status XML, and 2) exceptions/printfs of what *should* have been
directly available in the controller alias when constructing device
commandline arguments:

1) The primary (and only) IDE controller on a 440FX machinetype is
hardcoded to be "ide" in qemu.

2) The primary SATA controller on a 440FX machinetype is also
hardcoded to be "ide" in qemu.

3) On machinetypes that don't support multiple PCI buses, the PCI bus
is hardcoded in qemu to have the name "pci".

4) The first usb master controller is "usb", all others are the normal
"usb%d". (note that usb controllers that are not a "master" will have
the same index, and thus alias, as the master).

We needed to pass in the full domainDef and qemuCaps in order to
properly make the decisions about these exceptions.