ata_piix: constify pci_bits

pci_bits are not supposed to change at runtime. Functions
pci_test_config_bits() working with const 'struct pci_bits'.
So mark the non-const structs as const.

Signed-off-by: Arvind Yadav <[e-mail]>
Signed-off-by: Tejun Heo <[e-mail]>

drivers/ata/ata_piix.c

···
 	[ich8_2port_sata_byt]	= &ich8_2port_map_db,
 };
 
-static struct pci_bits piix_enable_bits[] = {
+static const struct pci_bits piix_enable_bits[] = {
 	{ 0x41U, 1U, 0x80UL, 0x80UL },	/* port 0 */
 	{ 0x43U, 1U, 0x80UL, 0x80UL },	/* port 1 */
 };