cleanup: remove pointless cylinder model update

In DivePlannerPointsModel::clear(), the cylinder model is
updated before it is cleared. This must be an artifact.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

qt-models/diveplannermodel.cpp

@@ -993,7 +993,6 @@ void DivePlannerPointsModel::clear()
 {
 	bool oldRecalc = setRecalc(false);
 
-	cylinders.updateDive(&displayed_dive);
 	beginResetModel();
 	divepoints.clear();
 	endResetModel();