scsi: qla2xxx: add ring buffer for tracing debug logs

Having this log in a ring buffer helps to diagnose qla2xxx driver and
firmware issues instead of having to reproduce the problem with
extended_logging enabled. This saves cycles and helps when it is hard
to reproduce problem.

Link: https://lore.kernel.org/r/1581557368-32080-1-git-send-email-rajan.shanmugavelu@oracle.com


Reviewed-by: Joe Jin <joe.jin@oracle.com>
Acked-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Rajan Shanmugavelu <rajan.shanmugavelu@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>