For divecomputers without samples don't lose other data for profile

We create a fake divecomputer in order to draw a reasonable profile, but
when setting that up we used an empty divecomputer instead of starting
with the one that we have. This lost data (e.g., the model name of the
dc).

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
DivingLog import: keep the dive computer name around

We simply set up the model attribute.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>