vhost-vdpa: check vhost_vdpa_set_vring_ready() return value

vhost-vdpa: check vhost_vdpa_set_vring_ready() return value

vhost_vdpa_set_vring_ready() could already fail, but if Linux's
patch [1] will be merged, it may fail with more chance if
userspace does not activate virtqueues before DRIVER_OK when
VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK is not negotiated.

So better check its return value anyway.

[1] https://lore.kernel.org/virtualization/20240206145154.118044-1-sgarzare@redhat.com/T/#u

Acked-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20240322092315.31885-1-sgarzare@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>