pata_radisys: fix mwdma_mask to exclude mwdma0

As noted by Alan:
>Your suspicions are correct here btw - the device can only do MWDMA1 and
>MWDMA2 (much like some PIIX devices)

Signed-off-by: Erik Inge Bolsø <[e-mail]>
Signed-off-by: Jeff Garzik <[e-mail]>

drivers/ata/pata_radisys.c

···
 	static const struct ata_port_info info = {
 		.flags		= ATA_FLAG_SLAVE_POSS,
 		.pio_mask	= ATA_PIO4,
-		.mwdma_mask	= ATA_MWDMA2, /* mwdma1-2 */
+		.mwdma_mask	= ATA_MWDMA12_ONLY,
 		.udma_mask	= ATA_UDMA24_ONLY,
 		.port_ops	= &radisys_pata_ops,
 	};