scsi: qla2xxx: Fix NVMe port discovery after a short device port loss

scsi: qla2xxx: Fix NVMe port discovery after a short device port loss

The following sequence of event leads to NVME port disappearing:

    - device port shut
    - nvme_fc_unregister_remoteport
    - device port online
    - remote port delete completes
    - relogin is scheduled
    - "post gidpn" message appears due to rscn generation # mismatch

In short, if a device comes back online sooner than an unregister
completion, a mismatch in rscn generation number occurs, which is not
handled correctly during device relogin. Fix this by starting with a redo
of GNL.

When ql2xextended_error_logging is enabled, the re-plugged device's
discovery stops with the following messages printed:

--8<--
qla2xxx [0000:41:00.0]-480d:3: Relogin scheduled.
qla2xxx [0000:41:00.0]-4800:3: DPC handler sleeping.
qla2xxx [0000:41:00.0]-2902:3: qla24xx_handle_relogin_event 21:00:00:24:ff:17:9e:91 DS 0 LS 7 P 0 del 2 cnfl
   (null) rscn 1|2 login 1|2 fl 1
qla2xxx [0000:41:00.0]-28e9:3: qla24xx_handle_relogin_event 1666 21:00:00:24:ff:17:9e:91 post gidpn
qla2xxx [0000:41:00.0]-480e:3: Relogin end.
--8<--

Signed-off-by: Arun Easi <aeasi@marvell.com>
Signed-off-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>