libxl: fix cold plugged PCI device with stubdomain

libxl: fix cold plugged PCI device with stubdomain

When libxl__device_pci_add() is called, stubdomain is already running,
even when still constructing the target domain. Previously, do_pci_add()
was called with 'starting' hardcoded to false, but now do_pci_add() shares
'starting' flag in pci_add_state for both target domain and stubdomain.

Fix this by resetting (local) 'starting' to false in pci_add_dm_done()
(previously part of do_pci_add()) when handling stubdomain, regardless
of pas->starting value.

Fixes: 11db56f9a6 (libxl_pci: Use libxl__ao_device with libxl__device_pci_add)
Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>