vdpa: validate device feature provisioning against supported class

Today when device features are explicitly provisioned, the features
user supplied may contain device class specific features that are
not supported by the parent management device. On the other hand,
when parent management device supports more than one class, the
device features to provision may be ambiguous if none of the class
specific attributes is provided at the same time. Validate these
cases and prompt appropriate user errors accordingly.

Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Message-Id: <1675725124-7375-5-git-send-email-si-wei.liu@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>