ppc4xx: Remove unreferenced file include/405_dimm.h

Signed-off-by: Stefan Roese <sr@denx.de>

include/405_dimm.h

@@ -1,4 +0,0 @@
-#ifndef _405_dimm_h_
-#define _405_dimm_h_
-long int walnut_dimm(void);
-#endif