[CELL] cell: add hardcoded spu vicinity information for QS20

This patch allows the use of spu affinity on QS20, whose
original FW does not provide affinity information.
This is done through two hardcoded arrays, and by reading the reg
property from each spu.

Signed-off-by: Andre Detsch <adetsch@br.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>