pwm: pxa: Remove pxa_pwm_enable/disable

pwm: pxa: Remove pxa_pwm_enable/disable

These functions are only acting as wrappers for clk_prepare_enable and
clk_disable_unprepare now, so remove them to simplify the driver.

Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Doug Brown <doug@schmorgal.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20221113233639.24244-2-doug@schmorgal.com
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>