pds_vdpa: add vdpa config client commands

These are the adminq commands that will be needed for
setting up and using the vDPA device.  There are a number
of commands defined in the FW's API, but by making use of
the FW's virtio BAR we only need a few of these commands
for vDPA support.

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230519215632.12343-9-shannon.nelson@amd.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>