The current script relies on a hardware reset pin to release the chip
from reset. Software reset is also possible and even required in case
the reset pin hasn't been wired to the J-Link connector on the board.
This patch adds an additional command line switch to nrfjprog.py that
uses the software reset mechanism of nrfjprog instead of pin reset.
Signed-off-by: Aapo Vienamo <aapo.vienamo@iki.fi>