ide: constify struct ide_port_info

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/pci/piix.c b/drivers/ide/pci/piix.c
index 450d3d5..9329d4a 100644
--- a/drivers/ide/pci/piix.c
+++ b/drivers/ide/pci/piix.c
@@ -396,7 +396,7 @@
 		.udma_mask	= udma, \
 	}
 
-static struct ide_port_info piix_pci_info[] __devinitdata = {
+static const struct ide_port_info piix_pci_info[] __devinitdata = {
 	/*  0 */ DECLARE_PIIX_DEV("PIIXa",	0x00),	/* no udma */
 	/*  1 */ DECLARE_PIIX_DEV("PIIXb",	0x00),	/* no udma */