virtio: vdpa: new SolidNET DPU driver.

This commit includes:
 1) The driver to manage the controlplane over vDPA bus.
 2) A HW monitor device to read health values from the DPU.

Signed-off-by: Alvaro Karsz <alvaro.karsz@solid-run.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230110165638.123745-4-alvaro.karsz@solid-run.com>
Message-Id: <20230209075128.78915-1-alvaro.karsz@solid-run.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>