ppc4xx: Consolidate PPC4xx EBC defines

This patch removes all EBC related defines from the PPC4xx headers
ppc405.h and ppc440.h and introduces a new header

include/asm-ppc/ppc4xx-ebc.h

with all those defines.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/include/ppc4xx.h b/include/ppc4xx.h
index 54897f7..ca0636c 100644
--- a/include/ppc4xx.h
+++ b/include/ppc4xx.h
@@ -53,6 +53,7 @@
 #endif
 
 #include <asm/ppc4xx-sdram.h>
+#include <asm/ppc4xx-ebc.h>
 
 /*
  * Macro for generating register field mnemonics