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

Change-Id: I2e7b756296e861e08cea846297f687a880daaf45
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/20355
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/soc/mediatek/mt8173/i2c.c

@@ -70,7 +70,7 @@ static struct mtk_i2c i2c[7] = {
 
 #define I2CTAG                "[I2C][PL] "
 
-#if CONFIG_DEBUG_I2C
+#if IS_ENABLED(CONFIG_DEBUG_I2C)
 #define I2CLOG(fmt, arg...)   printk(BIOS_INFO, I2CTAG fmt, ##arg)
 #else
 #define I2CLOG(fmt, arg...)