ppc4xx: Move ppc4xx headers to powerpc include directory

This patch moves some ppc4xx related headers from the common include
directory (include/) to the powerpc specific one
(arch/powerpc/include/asm/). This way to common include directory is not
so cluttered with files.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/board/mpl/mip405/mip405.c b/board/mpl/mip405/mip405.c
index 7400ca6..3db06e7 100644
--- a/board/mpl/mip405/mip405.c
+++ b/board/mpl/mip405/mip405.c
@@ -65,7 +65,7 @@
 #include <common.h>
 #include "mip405.h"
 #include <asm/processor.h>
-#include <4xx_i2c.h>
+#include <asm/ppc4xx-i2c.h>
 #include <miiphy.h>
 #include "../common/common_util.h"
 #include <stdio_dev.h>