[POWERPC] Celleb: consolidate spu management ops

Spu management ops in arch/platforms/cell/spu_priv1_mmio.h can be used
commonly in of based platform. This patch separates spu management ops
from native cell code and uses on celleb platform.

Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Kou Ishizaki <kou.ishizaki@toshiba.co.jp>
Signed-off-by: Paul Mackerras <paulus@samba.org>