Fix problem where in PIO_1 mode, state machines were not initialized

[aselle]

• N_ABC_MOTORS > 0 is proper condition. I was testing with Y_GANGED which exhibited the bug. With > 1 condition, y2_sm was unitialized.
• I removed the logic that checked if the sm was >= 3. If that was ever not true, it wouldn't work properly, because everything using the sm's later is hardcoded to the pio0 for the non primary axes.

[aselle]

Addressed the comments, thanks for the review!

[aselle]

Did you address this here? https://github.com/grblHAL/RP2040/commit/299068d9dc10ccf67add996a5ede97952d1fb4d1 If so, please close this.

[terjeio]

Yes, sorry for forgetting about this PR.