southbridge/intel/i82801ax: transition away from device_t

Replace the use of the old device_t definition inside
southbridge/intel/i82801ax.

Change-Id: I46f0cc92e1034f045988b42df7246f5d0c8d24fc
Signed-off-by: Antonello Dettori <dev@dettori.io>
Reviewed-on: https://review.coreboot.org/16484
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

src/southbridge/intel/i82801ax/early_smbus.c

@@ -25,7 +25,7 @@
 
 void enable_smbus(void)
 {
-	device_t dev;
+	pci_devfn_t dev;
 
 	/* Set the SMBus device statically (D31:F3). */
 	dev = PCI_DEV(0x0, 0x1f, 0x3);