WS2812: Support more than 5 pins in parallel mode (#455)

ws2812_parallel_program_init() contained an unneeded call to
sm_config_set_set_pins(). When this is called with the pin_count
parameter set to a value larger than 5, the set pin count value in the
pinctrl register overflows into the side-set pin count. This can result
in hard to diagnose issues where low numbered GPIO pins don't work as
expected.

There is an existing valid_params_if() check in sm_config_set_set_pins()
which would catch this error but it is ignored in Release builds.

This commit just removes this sm_config_set_set_pins() call as SET
commands aren't even used by the associated PIO code.

Discovered when trying to explain symptoms noted in this forum thread:
https://forums.raspberrypi.com/viewtopic.php?t=362071

Co-authored-by: Adam Green <[email protected]>

pio/ws2812/ws2812.pio

@@ -77,7 +77,6 @@ static inline void ws2812_parallel_program_init(PIO pio, uint sm, uint offset, u
     pio_sm_config c = ws2812_parallel_program_get_default_config(offset);
     sm_config_set_out_shift(&c, true, true, 32);
     sm_config_set_out_pins(&c, pin_base, pin_count);
-    sm_config_set_set_pins(&c, pin_base, pin_count);
     sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX);
 
     int cycles_per_bit = ws2812_parallel_T1 + ws2812_parallel_T2 + ws2812_parallel_T3;