drivers/i2c/ptn3460: Use cb_err in mb_adjust_cfg

Return generic coreboot error codes from the mb_adjust_cfg
callback used in mainboards instead of '-1' constant and
a driver-specific success-indicating define.

BUG=none
TEST=Boards siemens/mc_apl{1,4,5,7} and siemens/mc_ehl3
build correctly.

Change-Id: I5e0d4e67703db518ed239a845f43047f569b94ec
Signed-off-by: Jan Samek <jan.samek@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/72071
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>
diff --git a/src/drivers/i2c/ptn3460/ptn3460.c b/src/drivers/i2c/ptn3460/ptn3460.c
index 3ea41ba..31db8ad 100644
--- a/src/drivers/i2c/ptn3460/ptn3460.c
+++ b/src/drivers/i2c/ptn3460/ptn3460.c
@@ -108,7 +108,7 @@
 	}
 	/* Mainboard can modify the configuration data.
 	   Write back configuration data to PTN3460 if modified by mainboard */
-	if (mb_adjust_cfg(&cfg) == PTN_CFG_MODIFIED) {
+	if (mb_adjust_cfg(&cfg) == CB_SUCCESS) {
 		ptr = (uint8_t *)&cfg;
 		for (i = 0; i < sizeof(struct ptn_3460_config); i++) {
 			val = i2c_dev_writeb_at(dev, PTN_CONFIG_OFF + i, *ptr++);
@@ -131,9 +131,9 @@
 {
 	return 0;
 }
-__weak int mb_adjust_cfg(struct ptn_3460_config *cfg_ptr)
+__weak enum cb_err mb_adjust_cfg(struct ptn_3460_config *cfg_ptr)
 {
-	return 0;
+	return CB_ERR;
 }
 
 static struct device_operations ptn3460_ops = {