configure: Remove -nokia-developer option

There's no good reason to still differentiate between 'Nokia' developers,
and Qt developers outside of Nokia, inside configure. Just use
-developer-build -opensource -confirm-license.

Change-Id: I8726947dae0c70412eb52bf9d88eda4aa061ef26
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>