openconnect: Drop dead code for unsupported openconnect versions.
The minimum openconnect version we support is 3.99, whose API version as set in openconnect.h is 2.0, so we can remove code that is defined only for older API versions.
The minimum openconnect version we support is 3.99, whose API version as set in openconnect.h is 2.0, so we can remove code that is defined only for older API versions.