Fix neopixel for python version of adafruit_pixelbuf

[Neradoc]

Using the neokey on a board without builtin adafruit_pixelbuf (using the python version) I get that:

code.py output:
Traceback (most recent call last):
  File "code.py", line 9, in <module>
  File "adafruit_neokey/neokey1x4.py", line 64, in __init__
  File "adafruit_seesaw/neopixel.py", line 80, in __init__
TypeError: unexpected keyword argument 'size'

And indeed the size argument is called "n" in that version.
It's the positional argument anyway, no need for a name.

[tekktrik]

Perfect, nice fix! Probably worth fixing the adafruit_pixelbuf library at some point, but you're right, positional is fine (and what people are most likely to do).