scsi: qla2xxx: Add 28xx flash primary/secondary status/image mechanism

Includes the following:
- correction to 27xx image status struct;
- factoring of 27xx image status validating routines to make common;
- image status generation compare that works across zero wrap;
- bsg interface to report current active images (as loaded by driver).

Signed-off-by: Joe Carnuccio <joe.carnuccio@cavium.com>
Signed-off-by: Mike Hernandez <mhernandez@marvell.com>
Signed-off-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>