virtgpu does not return error for misconfigured virgl command
Description of problem:
When ```virgl_renderer_submit_cmd``` reports error, cmd->error should be set. Otherwise driver cannot know if there is error.
https://gitlab.com/qemu-project/qemu/-/blob/master/hw/display/virtio-gpu-virgl.c?ref_type=heads#L233

Probably 0x1200 (unspec) or 0x1205 (invalid param) should return as error. 


If there is problem in cmd virgl freezes drawing window.
Steps to reproduce:
1. Send misformated command to virgl over vgpu device
2.
3.
Additional information:
Misformated 3d commands stops opengl's drawings. Without returning error we cannot know any error, hence we cannot reset vgpu.