coreboot: Replace all IS_ENABLED(CONFIG_XXX) with CONFIG(XXX)

This patch is a raw application of

 find src/ -type f | xargs sed -i -e 's/IS_ENABLED\s*(CONFIG_/CONFIG(/g'

Change-Id: I6262d6d5c23cabe23c242b4f38d446b74fe16b88
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/31774
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/cpu/x86/mtrr/debug.c

@@ -197,6 +197,6 @@ static void _display_mtrrs(void)
 
 asmlinkage void display_mtrrs(void)
 {
-	if (IS_ENABLED(CONFIG_DISPLAY_MTRRS))
+	if (CONFIG(DISPLAY_MTRRS))
 		_display_mtrrs();
 }