scsi: csiostor: fix NULL pointer dereference in csio_vport_set_state()

Assign fc_vport to ln->fc_vport before calling csio_fcoe_alloc_vnp() to
avoid a NULL pointer dereference in csio_vport_set_state().

ln->fc_vport is dereferenced in csio_vport_set_state().

Signed-off-by: Varun Prakash <varun@chelsio.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>