scsi: qla2xxx: Relogin to target port on a cable swap

If user swaps one target port for another target port for same switch
port, the new target port is not being recognized by the driver. Current
code assumes that old Target port has recovered from link down. The fix
will ask switch what is the WWPN of a specific NportID (GPNID) rather
than assuming it's the same Target port which has came back.

Fixes: 726b8548 ("qla2xxx: Add framework for async fabric discovery")
Cc: <stable@vger.kernel.org> # 4.10+
Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>