[libata] ahci_platform: fix DT probing

The change in commit 904c04feaf13ed "ahci_platform: Add the board_ids..."
doesn't work for the DT probing case as platform_get_device_id returns
NULL. Pick the default ahci_port_info in this case.

Signed-off-by: Rob Herring <[e-mail]>
Acked-by: Anton Vorontsov <[e-mail]>
Cc: Richard Zhu <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Jeff Garzik <[e-mail]>

drivers/ata/ahci_platform.c

···
 	struct device *dev = &pdev->dev;
 	struct ahci_platform_data *pdata = dev_get_platdata(dev);
 	const struct platform_device_id *id = platform_get_device_id(pdev);
-	struct ata_port_info pi = ahci_port_info[id->driver_data];
+	struct ata_port_info pi = ahci_port_info[id ? id->driver_data : 0];
 	const struct ata_port_info *ppi[] = { &pi, NULL };
 	struct ahci_host_priv *hpriv;
 	struct ata_host *host;