UPSTREAM: regulator: pwm: Use pwm_get_args() where appropriate

UPSTREAM: regulator: pwm: Use pwm_get_args() where appropriate

The PWM framework has clarified the concept of reference PWM config (the
platform dependent config retrieved from the DT or the PWM lookup table)
and real PWM state.

Use pwm_get_args() when the PWM user wants to retrieve this reference
config and not the current state.

This is part of the rework allowing the PWM framework to support
hardware readout and expose real PWM state even when the PWM has just
been requested (before the user calls pwm_config/enable/disable()).

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
(cherry picked from 8c12ad8e916ee0477f7a0a0f00b0a87b9a21ebf7)

Conflicts:
	drivers/regulator/pwm-regulator.c

Change-Id: Id7fb1d823db7a0be207de4f0393e6c86df143335
Signed-off-by: David Wu <david.wu@rock-chips.com>