drm/tegra: Do not export tegra_bo_ops

These buffer object operations are never used outside of the GEM
implementation so there is no use in exporting them.

Signed-off-by: Thierry Reding <treding@nvidia.com>

diff --cc drivers/gpu/drm/tegra/gem.c
Simple merge

diff --cc drivers/gpu/drm/tegra/gem.h
Simple merge