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/sandburst/common/ppc440gx_i2c.c b/board/sandburst/common/ppc440gx_i2c.c
index 68acdd8..85b63fc 100644
--- a/board/sandburst/common/ppc440gx_i2c.c
+++ b/board/sandburst/common/ppc440gx_i2c.c
@@ -26,8 +26,8 @@
  * Sandburst Corporation.
  */
 #include <common.h>
-#include <ppc4xx.h>
-#include <4xx_i2c.h>
+#include <asm/ppc4xx.h>
+#include <asm/ppc4xx-i2c.h>
 #include <i2c.h>
 #include <command.h>
 #include "ppc440gx_i2c.h"