Skip VST version check to detect MIDI inputs

Skip VST version check to detect MIDI inputs

Some plugins return 0 from effGetVstVersion and are hence not detected
as instruments. e.g. VeeSeeVSTRack (VCV). This may also explain why MIDI
port of some other VSTs are not exposed.

Most VST2.4 return 2400, so checking  [effGetVstVersion] >=2 (and not 2000)
was incorrect to begin with.