Remove the explicit UTF-8 conversions

Thanks to commit bdbfdcdfa0fb ('Ask Qt 4 to use the UTF-8 codec as the
"codec for C strings"') we no longer need the explicit UTF-8 conversion
when creating QStrings from char *.

Suggested-by: Thiago Macieira <thiago@macieira.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>