Fix recently changed super-method-hierarchy command

[tgodzik]

This was changed by mistake by me, when doing some refactorings.

Found in lsp--text-document-position-params

I haven't tested it and if anyone could confirm it works I would be super thankful :pray:

[kurnevsky]

Thanks, works fine for me. Though for me it doesn't make a buffer active when it's opened from this command, but it's a separate issue.