armv7.h: Add <asm/io.h>

With a389531 we now call readl() from this file so add <asm/io.h> so
that we have a prototype for the function.

Signed-off-by: Tom Rini <trini@konsulko.com>

arch/arm/include/asm/armv7.h

@@ -58,6 +58,7 @@
 
 #ifndef __ASSEMBLY__
 #include <linux/types.h>
+#include <asm/io.h>
 
 /*
  * CP15 Barrier instructions