pwm: Support for duty_offset
Support a new abstraction for pwm configuration that allows to specify
the time between start of period and the raising edge of the signal
("duty offset").
This is used in a patch series by Trevor Gamblin for triggering an ADC
conversion and afterwards read out the result. See
https://lore.kernel.org/linux-iio/
20240909-ad7625_r1-v5-0-
60a397768b25@baylibre.com/
for more details.