virpci.c: use virPCIDeviceAddressPtr in virPCIDeviceListFindIndex()

virpci.c: use virPCIDeviceAddressPtr in virPCIDeviceListFindIndex()

We're going to need a way to remove a PCI Device from a list without having
a valid virPCIDevicePtr, because the device is missing from the host. This
means that virPCIDevicesListDel() must operate with a PCI Device address
instead.

Turns out that virPCIDevicesListDel() and its related functions only use
the virPCIDeviceAddressPtr of the virPCIDevicePtr, so this change is
simple to do and will not cause hassle in all other callers. Let's
start adapting virPCIDeviceListFindIndex() and crawl our way up to
virPCIDevicesListDel().

Reviewed-by: Laine Stump <laine@redhat.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>