[Feature Request] Implement PWM frequency option for newer ISSI drivers

[Thiird]

Newer ISSI led drivers like IS31FL3733B give the user the possibility to set the PWM frequency by manipulating the PFS register.

This can be used to avoid hearing a buzzing noise from the driver's decoupling capacitors when the led's brightness is set above a certain threshold.

ISSI itself speaks about this issue in the IS31FL3733B's datasheet, page 25/30.

I think eliminating the buzzing in software would be a better solution than using tantalum capacitors, because it wouldn't add cost to the project and it would let us take advantage of the hardware that we already have on hand.

Sample of the noise from a single driver setup.

I will personally make a build with a dual IS31FL3733B setup in the near future (the older version IS31FL3733 is being phased out and is hard to find), so I would be happy to test this feature myself once it's implemented.

[Thiird]

Closing issue as it has been addressed by #14983.