scsi: qla2xxx: Update flash read/write routine

This patch makes following changes to flash access routines:

- update return type for read_optrom
- use void instead of uint32_t * for buffer parameter in read
  and write optrom routines
- fix flash/nvram addressing

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