virtio: vdpa: vDPA driver for Marvell OCTEON DPU devices

This commit introduces a new vDPA driver specifically designed for
managing the virtio control plane over the vDPA bus for OCTEON DPU
devices. The driver consists of two layers:

1. Octep HW Layer (Octeon Endpoint): Responsible for handling hardware
operations and configurations related to the DPU device.

2. Octep Main Layer: Compliant with the vDPA bus framework, this layer
implements device operations for the vDPA bus. It handles device
probing, bus attachment, vring operations, and other relevant tasks.

Signed-off-by: Srujana Challa <schalla@marvell.com>
Signed-off-by: Vamsi Attunuru <vattunuru@marvell.com>
Signed-off-by: Shijith Thotton <sthotton@marvell.com>
Signed-off-by: Nithin Dabilpuram <ndabilpuram@marvell.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20240614144659.1776067-1-schalla@marvell.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>