Fix VMSTATE_PCI_DEVICE version

PCI device entries have to have a default version, not 2, because they are
used in the midle of other structures that can have _any_ version number.

We can't use proper versioning here until we have SubSections support.
Why we didn't noticed before?  Because in a PC, the only device ported with
a version less that 2 is piix_pm, and for that one, default pci values are
right.  If you use a virtio-console, you will see that its state it is not
loaded back.

Thanks to Amit Shah for reporting the problem and help debug the fix.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

hw/hw.h

diff --git a/hw/hw.h b/hw/hw.h
index 0ae4000..a0cb94e 100644
--- a/hw/hw.h
+++ b/hw/hw.h
@@ -408,7 +408,6 @@
 
 #define VMSTATE_PCI_DEVICE(_field, _state) {                         \
     .name       = (stringify(_field)),                               \
-    .version_id = 2,                                                 \
     .size       = sizeof(PCIDevice),                                 \
     .vmsd       = &vmstate_pci_device,                               \
     .flags      = VMS_STRUCT,                                        \