Fix PICO_SCANVIDEO_ENABLE_CLOCK_PIN without _ENABLE_DEN_PIN

[Daft-Freak]

Enable the side set pin if CLOCK is enabled instead of DEN and also set the function on the right pin if DEN is not enabled.

I've used this with an st7796s display in RGB "sync" mode.

[kilograham]

thanks; if i recall there is a count of pins used somewhere also (that are set to PIO) which is probably wrong too.

[Daft-Freak]

Extremely late reply, but it looks like I adjusted both pin_mask (function) and pin_count (dir).