soc/intel: Use config_of_path(SA_DEVFN_ROOT)

We do not want to disguise somewhat complex function
calls as simple macros.

Change-Id: I53324603c9ece1334c6e09d51338084166f7a585
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34299
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: David Guckian
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/icelake/pmc.c

@@ -135,8 +135,7 @@ static void pch_power_options(void)
 
 static void pmc_init(void *unused)
 {
-	struct device *dev = SA_DEV_ROOT;
-	config_t *config = dev->chip_info;
+	config_t *config = config_of_path(SA_DEVFN_ROOT);
 
 	rtc_init();