arch/io.h: Separate MMIO and PNP ops

Change-Id: Ie32f1d43168c277be46cdbd7fbfa2445d9899689
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/31699
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/console/post.c

@@ -14,12 +14,15 @@
  * GNU General Public License for more details.
  */
 
-#include <arch/io.h>
+#include <stdint.h>
 #include <elog.h>
 #include <console/console.h>
 #include <device/device.h>
 #include <pc80/mc146818rtc.h>
 #include <smp/spinlock.h>
+#if IS_ENABLED(CONFIG_POST_IO)
+#include <arch/io.h>
+#endif
 
 /* Write POST information */