scsi: qla2xxx: Fix duplicate switch's Nport ID entries

[ Upstream commit f3a03ee1102a44ccbd2c5de80a6e862ba23e9b55 ]

Current code relies on switch to provide a unique combination of WWPN +
NPORTID to tract an FC port.  This patch tries to detect a case where switch
data base can get corrupted where multiple WWPNs can have the same Nport ID.
The 1st Nport ID on the list will be kept while the duplicate Nport ID will be
discarded.

Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>