device/mmio.h: Add include file for MMIO ops

MMIO operations are arch-agnostic so the include
path should not be arch/.

Change-Id: I0fd70f5aeca02e98e96b980c3aca0819f5c44b98
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/31691
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/mainboard/emulation/qemu-armv7/mainboard.c b/src/mainboard/emulation/qemu-armv7/mainboard.c
index 857365b..08b9bf2 100644
--- a/src/mainboard/emulation/qemu-armv7/mainboard.c
+++ b/src/mainboard/emulation/qemu-armv7/mainboard.c
@@ -21,7 +21,7 @@
 #include <halt.h>
 #include "mainboard.h"
 #include <edid.h>
-#include <arch/io.h>
+#include <device/mmio.h>
 
 static void init_gfx(void)
 {