scsi: qla2xxx: Add a shadow variable to hold disc_state history of fcport

This patch adds a shadow variable to hold disc_state history for the fcport
and prints state transition when the logging is enabled.

Link: https://lore.kernel.org/r/20191217220617.28084-4-hmadhani@marvell.com


Signed-off-by: Shyam Sundar <ssundar@marvell.com>
Signed-off-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>