Add effienecy test to LV_ENABLE test

Run LV_ENABLE test at 1A and measure efficiency at the same time.

Fail test if efficiency is less than 0.6.

Adds two efficiency measurements, one when LV is off (which is hardcoded to -1 and does not make sense) and one when LV is on.

Fixes issue #9 (closed) .

Once merged this requires a counter issue in the dash guy to be displayed.

@zhicaiz This is untested could you please test it.