pwm: lpss-*: Make use of devm_pwmchip_alloc() function

This prepares the pwm-lpss drivers 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.

Reviewed-by: Andy Shevchenko <andy@kernel.org>
Link: https://lore.kernel.org/r/b567ab5dd992e361eb884fa6c2cac11be9c7dde3.1707900770.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

pwm: lpss: Rename pwm_lpss_probe() --> devm_pwm_lpss_probe()

The pwm_lpss_probe() uses managed resources. Show this to
the users explicitly by adding devm prefix to its name.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

pwm: lpss: Allow other drivers to enable PWM LPSS

The PWM LPSS device can be embedded in another device.
In order to enable it, allow that drivers to probe
a corresponding device.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>