On Tegra186, it is necessary to perform an SMC to fully flush all caches;
flushing/cleaning by set/way is not enough. Implement the required hook
to make this happen.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>