[POWERPC] cuimage for Bamboo board

Add a cuboot wrapper for the Bamboo board.  Additionally, we enable MAC
address fixups for both cuboot and treeboot.

This also removes some obsoleted linker declarations that have been
moved into ops.h

Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>