module: ignore NULL type

Just return in case module_load_qom_one(NULL) is called.
vga_interface_available() can do that.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-Id: <20200720100352.2477-3-kraxel@redhat.com>

util/module.c

@@ -275,6 +275,9 @@ void module_load_qom_one(const char *type)
 {
     int i;
 
+    if (!type) {
+        return;
+    }
     if (module_loaded_qom_all) {
         return;
     }