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/netstal/hcu5/sdram.c b/board/netstal/hcu5/sdram.c
index 0546cd7..e5ac46b 100644
--- a/board/netstal/hcu5/sdram.c
+++ b/board/netstal/hcu5/sdram.c
@@ -35,7 +35,7 @@
 #include <asm/io.h>
 #include <asm/mmu.h>
 #include <asm/cache.h>
-#include <ppc440.h>
+#include <asm/ppc440.h>
 
 void hcu_led_set(u32 value);
 void dcbz_area(u32 start_address, u32 num_bytes);