vdpa net: stop probing if cannot set features

vdpa net: stop probing if cannot set features

Otherwise it continues the CVQ isolation probing.

Fixes: 152128d646 ("vdpa: move CVQ isolation check to net_init_vhost_vdpa")
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20230915170836.3078172-3-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>