scsi: g_NCR5380: Reduce overrides[] from array to struct

Remove compile-time card type definition GENERIC_NCR5380_OVERRIDE.  Then
remove all code iterating the overrides[] array and reduce it to struct
card.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Acked-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>