This prepares the driver for further changes that will drop struct
pwm_chip chip from struct atmel_hlcdc_pwm. Use the pwm_chip as driver
data instead of the atmel_hlcdc_pwm to get access to the pwm_chip in
the .suspend() and .resume() callbacks and atmel_hlcdc_pwm_remove()
without using atmel->chip.

Link: https://lore.kernel.org/r/0e97342f15540c7330d405eaaf3e68baa8e1e488.1707900770.git.u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>