Fix profile display for dives with no samples

For dives with no samples, we crate a fake dive computer with a set of
made-up samples and use those to display the profile.

However, the actual calculations to do the maximum duration and depth
etc were always done with the "real" dive information, which is empty.
As a result, the scale of the plot ended up being bogus, and part of
the dive would be missing.

Trivially fix by just passing the same dive computer information to
calculate_max_limits() that we use for everything else.

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