Set default properties for Power: virtual console and scsi driver
Set default properties for Power: virtual console and scsi driver

This patch enables the virtual console for Power systems /dev/hvc0
and sets scsi bus and virtio-scsi model as default.
The virtual console hvc0 enables full console including dmesg.
High performance virtio-scsi driver keeps the efficient design of
virtio-blk with effective SCSI passthrough.

Change-Id: I0b5cd4a15d30f06fc7993555d91d6907bd1acbd7

group-policy/devstack,openstack-dev/devstack,nawawi/openstack,bswartz/devstack,bigswitch/devstack,openstack-dev/devstack,bswartz/devstack,dtroyer/devstack,samgoon/devstack,group-policy/devstack,Mahito/devstack,dirkmueller/devstack,noironetworks/devstack,noironetworks/devstack,dirkmueller/devstack,Mahito/devstack,richliu/devstack,bigswitch/devstack,samgoon/devstack,nawawi/openstack,dtroyer/devstack,richliu/devstack