Stepper broken due to change in Adafruit_CircuitPython_Motor

[caternuson]

Started here:
https://forums.adafruit.com/viewtopic.php?f=8&t=148916
and verified. This PR:
https://github.com/adafruit/Adafruit_CircuitPython_Motor/pull/23/files
changed the way the frequency value is checked. It now throws an Error instead of changing it.

The stepper setup here needs to set frequency on its PWMOut objects. This might be made easier if frequency could be passed in to PWMOut constructor:
https://github.com/adafruit/Adafruit_CircuitPython_seesaw/blob/master/adafruit_seesaw/pwmout.py#L29

[ladyada]

@siddacious heya can you check this and revert ? ive been swamped and unable to test

[siddacious]

Yup, I'll take a look.

[siddacious]

OOf. My bad. :|

[ladyada]

hiya this should be all fixed now!