superio/aspeed/ast2400: Fix Register Offset

According to the specification the register offset must be 0x71 instead
of 0x70.

Change-Id: Icf69ffc701a42a31a4545ce53c13e2c2554863e1
Signed-off-by: Christian Walter <christian.walter@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38565
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/superio/aspeed/ast2400/superio.c

@@ -35,7 +35,7 @@ static void ast2400_init(struct device *dev)
 		pnp_enter_conf_mode(dev);
 		pnp_set_logical_device(dev);
 		/* In ESPI mode must write 0 to IRQ level on every LDN */
-		pnp_write_config(dev, 0x70, 0);
+		pnp_write_config(dev, 0x71, 0);
 		pnp_exit_conf_mode(dev);
 	}