drm/tegra: vic: Fix unused-function warnings

The use of the old-style SET_RUNTIME_PM_OPS() and
SET_SYSTEM_SLEEP_PM_OPS() macros requires function definitions
to be hidden to avoid

drivers/gpu/drm/tegra/vic.c:326:12: error: 'vic_runtime_suspend' defined but not used [-Werror=unused-function]
  326 | static int vic_runtime_suspend(struct device *dev)
      |            ^~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/tegra/vic.c:292:12: error: 'vic_runtime_resume' defined but not used [-Werror=unused-function]
  292 | static int vic_runtime_resume(struct device *dev)
      |            ^~~~~~~~~~~~~~~~~~

Use the new-style SYSTEM_SLEEP_PM_OPS() and RUNTIME_PM_OPS() instead.

Fixes: 1e15f5b9 ("drm/tegra: vic: Stop channel on suspend")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>