CP-12982: Deduplicate some code in Device.PCI.bind
CP-12982: Deduplicate some code in Device.PCI.bind

This also calls FLR when moving a device from a vGPU driver to pciback,
which wasn't being done before.

Signed-off-by: John Else <37b74501daa612e48fea94f9846ed4ddeb6a8f07@citrix.com>

thomassa/xenopsd,euanh/xenopsd,koushikcgit/xenopsd,djs55/xenopsd,euanh/xenopsd,johnelse/xenopsd,euanh/xenopsd,thomassa/xenopsd,johnelse/xenopsd,koushikcgit/xenopsd,johnelse/xenopsd,djs55/xenopsd,koushikcgit/xenopsd,thomassa/xenopsd,djs55/xenopsd