vdpa: ifcvf: set pci driver data in probe

We should set the pci driver data in probe instead of the vdpa device
adding callback. Otherwise if no vDPA device is created we will lose
the pointer to the management device.

Fixes: 6b5df347

 ("vDPA/ifcvf: implement management netlink framework for ifcvf")
Tested-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220524055557.1938-1-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>