net/mlx5: Add Virtio Emulation related device capabilities

Add Virtio Emulation related fields to the device capabilities.

It includes a general bit to indicate whether Virtio Emulation is
supported and the capabilities structure itself.

Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Reviewed-by: Shahaf Shuler <shahafs@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>