sb/intel: Define CONFIG_FIXED_SMBUS_IO_BASE

Make it default to 0x400, which is what the touched southbridges use.

Change-Id: I95cb1730d5bf6f596ed1ca8e7dba40b6a9e882fe
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43037
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/src/southbridge/intel/i82801ix/smbus.c b/src/southbridge/intel/i82801ix/smbus.c
index c348ed8..815705d 100644
--- a/src/southbridge/intel/i82801ix/smbus.c
+++ b/src/southbridge/intel/i82801ix/smbus.c
@@ -49,7 +49,7 @@
 static void smbus_read_resources(struct device *dev)
 {
 	struct resource *res = new_resource(dev, PCI_BASE_ADDRESS_4);
-	res->base = SMBUS_IO_BASE;
+	res->base = CONFIG_FIXED_SMBUS_IO_BASE;
 	res->size = 32;
 	res->limit = res->base + res->size - 1;
 	res->flags = IORESOURCE_IO | IORESOURCE_FIXED | IORESOURCE_RESERVE |