clocksource/drivers/timer-ti-dm: Add flag to detect omap1

Let's make it clear that some features need to be tested currently on
omap1. Only omap1 still uses platform_data.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Link: https://lore.kernel.org/r/20220815131250.34603-9-tony@atomide.com


Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>