Set current limit bug while using LVPM

[ku121ma]

As per the title, a typo exists in LVPM.py that triggers a runtime error. The function raw_from_amps is defined in LVPM.py, but __raw_from_amps is incorrectly referenced in setPowerUpCurrentLimit and setRunTimeCurrentLimit.

https://github.com/msoon/PyMonsoon/blob/master/Monsoon/LVPM.py#L69
https://github.com/msoon/PyMonsoon/blob/master/Monsoon/LVPM.py#L74