Make 'get_dive_by_diveid()' work even for non-primary dive computers

It's only used by the Uemis importer, and Dirk always seems to import
his Uemis data first, so it wasn't very noticeable.  But if the Uemis
data wasn't the first dive computer, it would not find the dive.

Side note: just comparing deviceid is not correct.  We should pass in
the device model too.  But again, that will realistically never really
matter, since non-Uemis importers will generate complex SHA1 hashes of
the dive data for the dive ID, so a collision with the Uemis numbers is
very unlikely.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>