clocksource: Add Tegra186 timers support

clocksource: Add Tegra186 timers support

Currently this only supports a single watchdog, which uses a timer in
the background for countdown. Eventually the timers could be used for
various time-keeping tasks, but by default the architected timer will
already provide that functionality.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Kartik <kkartik@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/1656922422-25823-3-git-send-email-kkartik@nvidia.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>