vkd3d: Remove warning for setting NULL index buffer.

This is benign and easily gets spammed a TON.
We will warn if an indexed draw is actually made like this.

Signed-off-by: Hans-Kristian Arntzen <post@arntzen-software.no>

libs/vkd3d/command.c

@@ -7760,7 +7760,6 @@ static void STDMETHODCALLTYPE d3d12_command_list_IASetIndexBuffer(d3d12_command_
 
     if (!view)
     {
-        WARN("Got NULL index buffer view, indexed draw calls will be dropped.\n");
         list->has_valid_index_buffer = false;
         return;
     }