[PATCH] ppc32: Add missing initrd header on ppc440

This missing initrd header slipped though last time.

Signed-off-by: Stefan Roese <sr@denx.de>
Signed-off-by: Matt Porter <mporter@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>