clocksource/drivers/timer-ti-dm: Add support to get pwm current status

omap_dm_timer_ops provide support to configure the pwm but there is no
support to get the current status. For configuring pwm it is advised to
check the current hw status instead of relying on pwm framework. So
implement a new timer ops to get the current status of pwm.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Acked-by: Tony Lindgen <tony@atomide.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200305082715.15861-6-lokeshvutla@ti.com