The time.sleep() and time.monotonic() functions break the timer
interrupt on which PewPew10 display relies, so we can't use them
anymore. Instead I'm adding a time-keeping function to the display
code itself, which then can be used in pew.tick() internally.
I noticed that this code was referring to samd-specific functionality,
and isn't enabled except in one samd board (pewpew10). Move it.
There is incomplte support for _pew in mimxrt10xx which then caused build
errors; adding a #if guard to check for _pew being enabled fixes it.
The _pew module is not likely to be important on mimxrt but I'll leave the
choice to remove it to someone else.
