scsi: lpfc: Clarify FAWNN error message

Current message on FAWWN events is rather cryptic.

Expand the message to clarify its meaning.

Link: https://lore.kernel.org/r/20191105005708.7399-8-jsmart2021@gmail.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>