blackfin: include <linux/compiler.h> rather than define __iomem

The macro __iomem is defined in include/linux/compiler.h.
Let's include it rather than double __iomem defines.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Sonic Zhang <sonic.adi@gmail.com>
diff --git a/arch/blackfin/include/asm/io.h b/arch/blackfin/include/asm/io.h
index 69f08bc..aadb0d2 100644
--- a/arch/blackfin/include/asm/io.h
+++ b/arch/blackfin/include/asm/io.h
@@ -11,10 +11,9 @@
 
 #ifdef __KERNEL__
 
+#include <linux/compiler.h>
 #include <asm/blackfin.h>
 
-#define __iomem
-
 static inline void sync(void)
 {
 	SSYNC();