ARM: uniphier: include <linux/io.h> from dram_init.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>

arch/arm/mach-uniphier/dram_init.c

@@ -7,6 +7,7 @@
 
 #include <common.h>
 #include <linux/errno.h>
+#include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/printk.h>
 #include <linux/sizes.h>