buildsystem: Drop explicit (k)config.h includes

We have kconfig.h auto-included and it pulls config.h too.

Change-Id: I665a0a168b0d4d3b8f3a27203827b542769988da
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/17655
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins)

src/vendorcode/amd/pi/00730F01/Porting.h

@@ -278,7 +278,6 @@
 #include "gcc-intrin.h"
 
 #include <assert.h>
-#include <config.h>
 #include <console/console.h>
 #include <commonlib/loglevel.h>