scsi: hpsa: add support for legacy boards

Add support for legacy boards, ensuring to enable the driver for
those boards only when 'hpsa_allow_any' is set.
The attribute 'legacy_board' is set to '1' if the device is
a legacy board, and '0' otherwise.

Signed-off-by: Hannes Reinecke <hare@suse.com>
Acked-by: Don Brace <don.brace@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>