Andreas Kling authored Jul 12, 2019 and Aleksander Morgado committed Jul 15, 2019

Some Telit modems (e.g LM940) have multiple firmwares to choose from.
This patch implements the parts of the GAS service (0xE8) that are needed
to list the active FW, list all FW, and set a new active FW.

These messages roughly correspond to the AT#GETFW and AT#ACTIVEFW commands.