drm/amdgpu: Use lockless gem BO free callback

No dev->struct_mutex anywhere to be seen.

Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Acked-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1461691808-12414-11-git-send-email-daniel.vetter@ffwll.ch

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

@@ -514,7 +514,7 @@ static struct drm_driver kms_driver = {
 	.irq_uninstall = amdgpu_irq_uninstall,
 	.irq_handler = amdgpu_irq_handler,
 	.ioctls = amdgpu_ioctls_kms,
-	.gem_free_object = amdgpu_gem_object_free,
+	.gem_free_object_unlocked = amdgpu_gem_object_free,
 	.gem_open_object = amdgpu_gem_object_open,
 	.gem_close_object = amdgpu_gem_object_close,
 	.dumb_create = amdgpu_mode_dumb_create,