Move the parsing part of radioshack-dmm into a separate protocol
parser, following the model from hardware/common/dmm.
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
The Fortune Semiconductor FS9721_LP3 and FS9721B/Q100 DMM chips are very
similar and the protocol looks identical.
Tested on a Voltcraft VC-820 (FS9721_LP3) with the uni-t-dmm driver
(needs some small changes, tbd).