rp2350: missing PWM implementation

[eliasnaur]

The machine.PWM* variables are not available when building for -target pico2, but are available when building for -target pico.

Is this an oversight in the rp2350 port or did I miss it? I see machine_rp2040_pwm.go, but nothing for rp2350. I would expect them to be similar, or even share code like the machine_rp2_*.go implementations.

[deadprogram]

One bi-product of PR #4723 is adding exactly that @eliasnaur

[eliasnaur]

Fixed by #4728.