idpf: fix aux device unplugging when rdma is not supported by vport

If vport flags do not contain VIRTCHNL2_VPORT_ENABLE_RDMA, driver does not
allocate vdev_info for this vport. This leads to kernel NULL pointer
dereference in idpf_idc_vport_dev_down(), which references vdev_info for
every vport regardless.

Check, if vdev_info was ever allocated before unplugging aux device.

Fixes: be91128c579c ("idpf: implement RDMA vport auxiliary dev create, init, and destroy")
Reviewed-by: Madhu Chittim <[e-mail]>
Signed-off-by: Larysa Zaremba <[e-mail]>
Reviewed-by: Paul Menzel <[e-mail]>
Reviewed-by: Aleksandr Loktionov <[e-mail]>
Tested-by: Krishneil Singh <[e-mail]>
Signed-off-by: Tony Nguyen <[e-mail]>

drivers/net/ethernet/intel/idpf/idpf_idc.c

···
 	for (i = 0; i < adapter->num_alloc_vports; i++) {
 		struct idpf_vport *vport = adapter->vports[i];
 
-		if (!vport)
+		if (!vport || !vport->vdev_info)
 			continue;
 
 		idpf_unplug_aux_dev(vport->vdev_info->adev);