drm: Drop drm_gem_object_put_locked()

Now that no one is using it, remove it.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://lore.kernel.org/r/20210728010632.2633470-5-robdclark@gmail.com


Signed-off-by: Rob Clark <robdclark@chromium.org>