vm start/stop: cleanup passed-through pci devices in more situations

vm start/stop: cleanup passed-through pci devices in more situations

if the preparing of PCI devices or the start of the VM fails, we need
to cleanup the PCI devices (reservations *and* mdevs), or else it
might happen that there are leftovers which must be manually removed.

to include also mdevs now, refactor the cleanup code from
'vm_stop_cleanup' into it's own function, and call that instead of
only 'remove_pci_reservation'

also simplifies the code, such that it now removes all PCI ids
reserved for that VMID, since we cannot have multiple VMs with the
same VMID anyway

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>