ARM: UniPhier: replace <asm/io.h> with <linux/io.h>

In the Linux coding style, it is recommended to include <linux/io.h>
rather than <asm/io.h>.  Follow this trend.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/arch/arm/mach-uniphier/ph1-ld4/ddrphy_init.c b/arch/arm/mach-uniphier/ph1-ld4/ddrphy_init.c
index a47e87a..2add8fa 100644
--- a/arch/arm/mach-uniphier/ph1-ld4/ddrphy_init.c
+++ b/arch/arm/mach-uniphier/ph1-ld4/ddrphy_init.c
@@ -1,11 +1,11 @@
 /*
- * Copyright (C) 2014 Panasonic Corporation
+ * Copyright (C) 2014-2015 Masahiro Yamada <yamada.masahiro@socionext.com>
  *
  * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #include <linux/types.h>
-#include <asm/io.h>
+#include <linux/io.h>
 #include <mach/ddrphy-regs.h>
 
 void ddrphy_init(struct ddrphy __iomem *phy, int freq, int size)