src/superio: Use 'PNP_IDX_*' macros instead of magic numbers

Change-Id: I2f8d6d9e8b6e84bb6c2b4e73b0fbeca476130d05
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44833
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/superio/ite/it8772f/early_init.c

@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 
 #include <arch/io.h>
+#include <device/pnp_def.h>
 #include <device/pnp_ops.h>
 
 #include "it8772f.h"
@@ -27,7 +28,7 @@ void it8772f_ac_resume_southbridge(pnp_devfn_t dev)
 {
 	it8772f_enter_conf(dev);
 	pnp_write_config(dev, IT8772F_CONFIG_REG_LDN, IT8772F_EC);
-	pnp_write_config(dev, 0xf4, 0x60);
+	pnp_write_config(dev, PNP_IDX_MSC4, 0x60);
 	it8772f_exit_conf(dev);
 }