PCI: hv: Fix a timing issue which causes kdump to fail occasionally

Kdump could fail sometime on Hyper-V guest because the retry in
hv_pci_enter_d0() releases child device structures in hv_pci_bus_exit().

Although there is a second asynchronous device relations message sending
from the host, if this message arrives to the guest after
hv_send_resource_allocated() is called, the retry would fail.

Fix the problem by moving retry to hv_pci_probe() and start the retry
from hv_pci_query_relations() call.  This will cause a device relations
message to arrive to the guest synchronously; the guest would then be
able to rebuild the child device structures before calling
hv_send_resource_allocated().

Link: https://lore.kernel.org/r/20200727071731.18516-1-weh@microsoft.com


Fixes: c81992e7 ("PCI: hv: Retry PCI bus D0 entry on invalid device state")
Signed-off-by: Wei Hu <weh@microsoft.com>
[lorenzo.pieralisi@arm.com: fixed a comment and commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>