[FFmpeg-soc] codec long names

[Diego Biurrun]

Hi all,

this is just a quick reminder that we recently added codec long names to
libavcodec and all the decoders and encoders you are implementing should
have one as well in their AVCodec declaration.

For example:

.name = "mp3",
.long_name = NULL_IF_CONFIG_SMALL("MP3 (MPEG audio layer 3)"),

Please add something like this if you haven't already, it will be one
less issue coming up during final reviews.

Diego