mainboard/[m-w]: add IS_ENABLED() around Kconfig symbol references

Change-Id: Ifba3257b0328d0b6ad1bee9bf885683998df5851
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/20344
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/mainboard/samsung/lumpy/acpi_tables.c

@@ -25,7 +25,7 @@
 #include <device/pci.h>
 #include <device/pci_ids.h>
 #include <ec/acpi/ec.h>
-#if CONFIG_CHROMEOS
+#if IS_ENABLED(CONFIG_CHROMEOS)
 #include <vendorcode/google/chromeos/gnvs.h>
 #endif