scsi: lpfc: Decrement ndlp kref after FDISC retries exhausted

The kref for Fabric_DID ndlps is not decremented after repeated FDISC
failures and exhausting maximum allowed retries.  This can leave the
ndlp lingering unnecessarily.  Add a test and set bit operation for the
NLP_DROPPED flag. If not previously set, then a kref is decremented. The
ndlp is freed when the remaining reference for the completing ELS is
put.

Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Message-ID: <20250915180811.137530-6-justintee8345@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>