southbridge/amd: add IS_ENABLED() around Kconfig symbol references

Change-Id: I8fabb7331435eb518a5c95cb29c4ff5ca98560d2
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/20349
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/southbridge/amd/agesa/hudson/hudson.c

@@ -181,7 +181,7 @@ static void hudson_init(void *chip_info)
 
 static void hudson_final(void *chip_info)
 {
-#if !CONFIG_ACPI_ENABLE_THERMAL_ZONE
+#if !IS_ENABLED(CONFIG_ACPI_ENABLE_THERMAL_ZONE)
 #if IS_ENABLED(CONFIG_HUDSON_IMC_FWM)
 	/* AMD AGESA does not enable thermal zone, so we enable it here. */
 	enable_imc_thermal_zone();