This prepares the pwm-atmel-hlcdc driver to further changes of the pwm
core outlined in the commit introducing devm_pwmchip_alloc(). There is
no intended semantical change and the driver should behave as before.

Link: https://lore.kernel.org/r/4724c6a0f052160ac80ba5a3065c9470778b7457.1707900770.git.u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>