clk: pwm: Convert to use pwm_apply_might_sleep()

clk: pwm: Convert to use pwm_apply_might_sleep()

pwm_config() is an old function that I'd like to remove. So convert this
driver to use pwm_apply_might_sleep().

There is a minor change in behaviour as the explicitly calculated
duty_cycle used an uprounding division while pwm_set_relative_duty_cycle()
rounds down. I don't expect that difference to matter in practice though.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/f194fad5ee8bdd3fda6159324524979729683653.1746006578.git.ukleinek@baylibre.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>