Input: max8997 - convert to modern way to get a reference to a PWM

Input: max8997 - convert to modern way to get a reference to a PWM

pwm_request() isn't recommended to be used any more because it relies on
global IDs for the PWM which comes with different difficulties.

The new way to do things is to find the right PWM using a reference from
the platform device. (This can be created either using a device-tree
or a platform lookup table, see e.g. commit 5a4412d4a82f ("ARM: pxa:
tavorevb: Use PWM lookup table") how to do this.)

There are no in-tree users, so there are no other code locations that need
adaption.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20221117073543.3790449-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>