scsi: lpfc: Save FPIN frequency statistics upon receipt of peer cgn notifications

FPIN frequency is provided by the fabric in peer congestion notifications.

Currently, the frequency is only logged in a message, but it should also be
saved into the phba's cgn_fpin statistics member for proper application
functionality.

Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Link: https://lore.kernel.org/r/20240131185112.149731-10-justintee8345@gmail.com


Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>