nport_free for an empty nport hangs the state machine waiting for mbox
completion if nport is not yet attached thinking that it is attaching right
now. Add a check for nport attaching state and complete nport free.
Link: https://lore.kernel.org/r/20210914105539.6942-3-d.bogdanov@yadro.com
Reviewed-by: Ram Vegesna <ram.vegesna@broadcom.com>
Signed-off-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>