Rearrange VGA/IDE controller address reservation

Rearrange VGA/IDE controller address reservation

The first VGA and IDE devices need to have fixed PCI address
reservations. Currently this is handled inline with the other
non-primary VGA/IDE devices. The fixed virtio balloon device
at slot 3, ensures auto-assignment skips the slots 1/2. The
virtio address will shortly become configurable though. This
means the reservation of fixed slots needs to be done upfront
to ensure that they don't get re-used for other devices.

This is more or less reverting the previous changeset:

  commit 83acdeaf173b2a1206b755c1ab317cac36facd90
  Author: Daniel P. Berrange <berrange@redhat.com>
  Date:   Wed Feb 3 16:11:29 2010 +0000

  Fix restore of QEMU guests with PCI device reservation

The difference is that this time, instead of unconditionally
reserving the address, we only reserve the address if it was
initially type=none. Addresses of type=pci were handled
earlier in process by qemuDomainPCIAddressSetCreate(). This
ensures restore step doesn't have problems

* src/qemu/qemu_conf.c: Reserve first VGA + IDE address
  upfront