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

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 <madhu.chittim@intel.com>
Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>