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/csb472/csb472.c b/board/csb472/csb472.c
index c138b0d..25709f2 100644
--- a/board/csb472/csb472.c
+++ b/board/csb472/csb472.c
@@ -25,7 +25,7 @@
 #include <asm/processor.h>
 #include <i2c.h>
 #include <miiphy.h>
-#include <ppc4xx_enet.h>
+#include <asm/ppc4xx-emac.h>
 
 void sdram_init(void);