Remove unnecessary check in pio_encode_sideset_opt

[ldursw]

When compiling with -O3 -Wall -Wextra a warning is emitted about a comparison always being true. sideset_bit_count is unsigned so it can't be negative. Just remove the comparison to fix the warning.

pico-sdk/src/rp2_common/hardware_pio/include/hardware/pio_instructions.h: In function 'uint pio_encode_sideset_opt(uint, uint)':
pico-sdk/src/rp2_common/hardware_pio/include/hardware/pio_instructions.h:151:57: error: comparison of unsigned expression in '>= 0' is always true [-Werror=type-limits]
  151 |     valid_params_if(PIO_INSTRUCTIONS, sideset_bit_count >= 0 && sideset_bit_count <= 4);
      |                                       ~~~~~~~~~~~~~~~~~~^~~~

[lurch]

Duplicate of #2608 ?

[ldursw]

Yes. It is the same as #2608. Closing this PR in favor of the older one.