src: Get rid of duplicated includes

Change-Id: I252a1cd77bf647477edb7dddadb7e527de872439
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/29582
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>

src/southbridge/intel/ibexpeak/smihandler.c

@@ -34,7 +34,6 @@
  */
 #include <northbridge/intel/nehalem/nehalem.h>
 #include <southbridge/intel/common/gpio.h>
-#include <arch/io.h>
 
 /* While we read PMBASE dynamically in case it changed, let's
  * initialize it with a sane value