avformat/utils: Combine identical statements

avformat/utils: Combine identical statements

This would only make a difference in case the first attempt to
initialize the encoder failed and the second succeeded. The only
reason I can think of for this to happen is that the options (in
particular the codec whitelist) are not used for the second try
and that obviously implies that we should not even try a second time
to open the decoder.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>