ieee1275: Implement vec5 for cas negotiation

ieee1275: Implement vec5 for cas negotiation

As a legacy support, if the vector 5 is not implemented, Power Hypervisor will
consider the max CPUs as 64 instead 256 currently supported during
client-architecture-support negotiation.

This patch implements the vector 5 and set the MAX CPUs to 256 while setting the
others values to 0 (default).

Signed-off-by: Diego Domingos <diegodo@linux.vnet.ibm.com>
Acked-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Avnish Chouhan <avnish@linux.vnet.ibm.com>
Tested-by: Nageswara R Sastry <rnsastry@linux.ibm.com>
Reviewed-by: Robbie Harwood <rharwood@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>