Enzyme extension unnecessarily computing original result

[wsmoses]

https://github.com/TuringLang/NormalizingFlows.jl/blob/58d3e57e66872274a1b6f46ffe68fc54da642d90/ext/NormalizingFlowsEnzymeExt.jl#L21

This line can be weakened from ReverseWithPrimal to just Reverse, since you don't use the result.

Moreover the issue referenced in the comments above have been closed/resolved