Only the V2 header contains a serial number, and there are also cases
where the serial number hasn't been filled in correctly.

Libdivecomputer doesn't use the actual model number for parsing the
Divesoft dives, so hardcoding the Freedom works fine. The main
disadvantage is that all imported dives will show the Divesoft Freedom
as their dive computer model.

Signed-off-by: Jef Driesen <jef@libdivecomputer.org>

Now when the descriptor always will use divesoft_freedom_model,
the dc model string will be misleading.

By just including vendor and that it's imported from a file,
it will be correct.

Signed-off-by: Anton Lundin <glance@ac2.se>