libata: fix G5 SATA broken on -rc5

Fix G5 SATA irq 18: nobody cared, reported on -rc5 by Olaf Hering:
fixlet to a57c1bad libata-sff:
Fix oops reported in kerneloops.org for pnp devices with no ctl
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Acked-by: NAlan Cox <alan@lxorguk.ukuu.org.uk>
Tested-by: NOlaf Hering <olaf@aepfle.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/ata/libata-sff.c

@@ -278,7 +278,7 @@ static u8 ata_sff_irq_status(struct ata_port *ap)
 		    	return status;
 	}
 	/* Clear INTRQ latch */
-	status = ata_sff_check_status(ap);
+	status = ap->ops->sff_check_status(ap);
 	return status;
 }