[FFmpeg-cvslog] avcodec/nvenc: avoid failing b_ref_mode check when unset

ffmpeg | branch: release/6.0 | Timo Rothenpieler | Fri Mar 10 13:09:10 2023 +0100| [916bdc0f197de7ea24d30f3f3c284e4332dd3720] | committer: Timo Rothenpieler avcodec/nvenc: avoid failing b_ref_mode check when unset >

[FFmpeg-cvslog] avcodec/nvenc: avoid failing b_ref_mode check when unset

ffmpeg | branch: master | Timo Rothenpieler | Fri Mar 10 13:09:10 2023 +0100| [7a8560cb22dd9f5c54df71af3fef26db9a2a28b0] | committer: Timo Rothenpieler avcodec/nvenc: avoid failing b_ref_mode check when unset >