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/drivers/ricoh/rce822/rce822.c

@@ -14,7 +14,6 @@
  * GNU General Public License for more details.
  */
 
-#include <kconfig.h>
 #include <console/console.h>
 #include <device/device.h>
 #include <device/pci.h>