Currently, firmware revision string is obtained via AT+CGMR or AT+GMR
commands from the default mm-broadband-modem. For a class of Telit
modems however this command does not return the actual Telit Software
Package version, but the "Modem FW Version", which is only a component
of the whole firmware. For this class of modems, the correct string is
obtained with "AT#SWPKGV" command.
This change overrides load_revision* functions to add the ability to
parse "AT#SWPKGV" command for the modems that support it, and falls back
to the same logic that was implemented in mm-broadband-modem otherwise.
Carlo Lobrano
3df96a4255