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/arch/powerpc/cpu/ppc4xx/fdt.c b/arch/powerpc/cpu/ppc4xx/fdt.c
index 15a184b..90c7e19 100644
--- a/arch/powerpc/cpu/ppc4xx/fdt.c
+++ b/arch/powerpc/cpu/ppc4xx/fdt.c
@@ -25,7 +25,7 @@
 #include <watchdog.h>
 #include <command.h>
 #include <asm/cache.h>
-#include <ppc4xx.h>
+#include <asm/ppc4xx.h>
 
 #if defined(CONFIG_OF_LIBFDT) && defined(CONFIG_OF_BOARD_SETUP)
 #include <libfdt.h>