ARM: uniphier: include <linux/io.h> from boot-device.c

This file calls readl(), so needs to include <linux/io.h>.
Currently, it relies on someone else including it.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/arch/arm/mach-uniphier/boot-device/boot-device.c b/arch/arm/mach-uniphier/boot-device/boot-device.c
index c8339db..5930215 100644
--- a/arch/arm/mach-uniphier/boot-device/boot-device.c
+++ b/arch/arm/mach-uniphier/boot-device/boot-device.c
@@ -7,6 +7,7 @@
 #include <common.h>
 #include <spl.h>
 #include <stdio.h>
+#include <linux/io.h>
 #include <linux/log2.h>
 
 #include "../init.h"