scsi: lpfc: Fix lpfc_els_retry() possible null pointer dereference

scsi: lpfc: Fix lpfc_els_retry() possible null pointer dereference

Driver crashed in lpfc_debugfs_disc_trc() due to null ndlp pointer.  In
some calling cases, the ndlp is null and the did is looked up.

Fix by using the local did variable that is set appropriately based on ndlp
value.

Link: https://lore.kernel.org/r/20210301171821.3427-7-jsmart2021@gmail.com
Co-developed-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>