src/include: add IS_ENABLED() around Kconfig symbol references

Change-Id: I2fbe6376a1cf98d328464556917638a5679641d2
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/20354
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
diff --git a/src/include/device/device.h b/src/include/device/device.h
index 5bc4d1c..242d297 100644
--- a/src/include/device/device.h
+++ b/src/include/device/device.h
@@ -53,7 +53,7 @@
 	void (*disable)(device_t dev);
 	void (*set_link)(device_t dev, unsigned int link);
 	void (*reset_bus)(struct bus *bus);
-#if CONFIG_GENERATE_SMBIOS_TABLES
+#if IS_ENABLED(CONFIG_GENERATE_SMBIOS_TABLES)
 	int (*get_smbios_data)(device_t dev, int *handle,
 		unsigned long *current);
 	void (*get_smbios_strings)(device_t dev, struct smbios_type11 *t);
@@ -163,7 +163,7 @@
 
 extern const char mainboard_name[];
 
-#if CONFIG_GFXUMA
+#if IS_ENABLED(CONFIG_GFXUMA)
 /* IGD UMA memory */
 extern uint64_t uma_memory_base;
 extern uint64_t uma_memory_size;