drm/amdgpu: fix mutex list null pointer reference

Fix NULL pointer reference.

Signed-off-by: Pixel Ding <[e-mail]>
Signed-off-by: Xiangliang Yu <[e-mail]>
Reviewed-by: Alex Deucher <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

···
 
 	DRM_INFO("amdgpu: finishing device.\n");
 	adev->shutdown = true;
-	drm_crtc_force_disable_all(adev->ddev);
+	if (adev->mode_info.mode_config_initialized)
+		drm_crtc_force_disable_all(adev->ddev);
 	/* evict vram memory */
 	amdgpu_bo_evict_vram(adev);
 	amdgpu_ib_pool_fini(adev);