rp: don't use SetConfig trait in PWM and PIO.

It was intended to allow changing baudrate on shared spi/i2c. There's no
advantage in using it for PWM or PIO, and makes it less usable because you have to
have `embassy-embedded-hal` as a dep to use it.

examples/rp/src/bin/ws2812-pio.rs

@@ -3,7 +3,6 @@
 #![feature(type_alias_impl_trait)]
 
 use defmt::*;
-use embassy_embedded_hal::SetConfig;
 use embassy_executor::Spawner;
 use embassy_rp::pio::{Common, Config, FifoJoin, Instance, Pio, PioPin, ShiftConfig, ShiftDirection, StateMachine};
 use embassy_rp::relocate::RelocatedProgram;