ARM: tegra: Remove flow controller programming

This particular code had no effect on WFI execution. It only
asserts/de-asserts signal to tegra "legacy" CPU idle stats
monitor, which we are no longer using (cpufreq is based on
kernel s/w idle stats instead).

Signed-off-by: Prashant Gaikwad <pgaikwad@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>