arch/io.h: Drop unnecessary include

Change-Id: I91158452680586ac676ea11c8589062880a31f91
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/31692
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/arch/arm/armv7/mmu.c

@@ -36,7 +36,6 @@
 #include <console/console.h>
 
 #include <arch/cache.h>
-#include <arch/io.h>
 
 #if IS_ENABLED(CONFIG_ARM_LPAE)
 /* See B3.6.2 of ARMv7 Architecture Reference Manual */