[libata] pata_rb532_cf: fix signature of the xfer function

Per definition, this function should return the number of bytes
consumed. As the original parameter "buflen" is being decremented inside
the read/write loop, save it in "retlen" at the beginning.

Signed-off-by: Phil Sutter <[e-mail]>
Acked-by: Sergei Shtyltov <[e-mail]>
Acked-by: Bartlomiej Zolnierkiewicz <[e-mail]>
Acked-by: Florian Fainelli <[e-mail]>
Signed-off-by: Jeff Garzik <[e-mail]>

drivers/ata/pata_rb532_cf.c

···
 	rb532_pata_finish_io(ap);
 }
 
-static void rb532_pata_data_xfer(struct ata_device *adev, unsigned char *buf,
+static unsigned int rb532_pata_data_xfer(struct ata_device *adev, unsigned char *buf,
 				unsigned int buflen, int write_data)
 {
 	struct ata_port *ap = adev->link->ap;
 	void __iomem *ioaddr = ap->ioaddr.data_addr;
+	int retlen = buflen;
 
 	if (write_data) {
 		for (; buflen > 0; buflen--, buf++)
···
 	}
 
 	rb532_pata_finish_io(adev->link->ap);
+	return retlen;
 }
 
 static void rb532_pata_freeze(struct ata_port *ap)