vl: fix "type is NULL" in -vga help

Don't pass NULL to module_object_class_by_name(), when the interface is
unavailable.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240715114420.2062870-1-marcandre.lureau@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
1 file changed