libata: dev_config does not need ap and adev passing

It used to be impossible to get from ata_device to ata_port but that is
no longer true. Various methods have been cleaned up over time but
dev_config still takes both and most users don't need both anyway. Tidy
this one up

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/sata_sil24.c b/drivers/ata/sata_sil24.c
index 5614df8..6698c74 100644
--- a/drivers/ata/sata_sil24.c
+++ b/drivers/ata/sata_sil24.c
@@ -323,7 +323,7 @@
 	struct ata_taskfile tf;			/* Cached taskfile registers */
 };
 
-static void sil24_dev_config(struct ata_port *ap, struct ata_device *dev);
+static void sil24_dev_config(struct ata_device *dev);
 static u8 sil24_check_status(struct ata_port *ap);
 static u32 sil24_scr_read(struct ata_port *ap, unsigned sc_reg);
 static void sil24_scr_write(struct ata_port *ap, unsigned sc_reg, u32 val);
@@ -462,9 +462,9 @@
 	return tag;
 }
 
-static void sil24_dev_config(struct ata_port *ap, struct ata_device *dev)
+static void sil24_dev_config(struct ata_device *dev)
 {
-	void __iomem *port = ap->ioaddr.cmd_addr;
+	void __iomem *port = dev->ap->ioaddr.cmd_addr;
 
 	if (dev->cdb_len == 16)
 		writel(PORT_CS_CDB16, port + PORT_CTRL_STAT);