py/modmath: Simplify handling of positional args to reduce code size.
py/modmath: Simplify handling of positional args to reduce code size.

As a general pattern, required positional arguments that are not named do
not need to be parsed using mp_arg_parse_all().

Signed-off-by: Damien George <99e6b749acbfbe2a596df99e91d24d6e1fdbee00@micropython.org>

henriknelson/micropython,bvernoux/micropython,bvernoux/micropython,bvernoux/micropython,adafruit/circuitpython,henriknelson/micropython,adafruit/circuitpython,adafruit/circuitpython,adafruit/circuitpython,henriknelson/micropython,bvernoux/micropython,henriknelson/micropython,adafruit/circuitpython,henriknelson/micropython,adafruit/circuitpython,bvernoux/micropython