obs-ffmpeg: Mark FFmpeg NVENC as internal

Because we implemented the fallback for rescaling, there's no need to
show FFmpeg NVENC anymore.

plugins/obs-ffmpeg/obs-ffmpeg-nvenc.c

@@ -570,5 +570,5 @@ struct obs_encoder_info nvenc_encoder_info = {
 	.get_extra_data = nvenc_extra_data,
 	.get_sei_data = nvenc_sei_data,
 	.get_video_info = nvenc_video_info,
-	.caps = OBS_ENCODER_CAP_DYN_BITRATE,
+	.caps = OBS_ENCODER_CAP_DYN_BITRATE | OBS_ENCODER_CAP_INTERNAL,
 };