Revert "avutil/channel_layout: av_channel_layout_describe_bprint: Check for buffer end"

The doxy for av_channel_layout_describe() states that the user should look
at the return value to check if the string was truncated. Returning an error
code in this scenario goes against this and is an API break.

A proper fix for the timeout was applied to the Matroska demuxer in 94901a9518.

This reverts commit 8154cb7c2f.

libavutil/channel_layout.c

@@ -757,10 +757,6 @@ int av_channel_layout_describe_bprint(const AVChannelLayout *channel_layout,
             if (channel_layout->order == AV_CHANNEL_ORDER_CUSTOM &&
                 channel_layout->u.map[i].name[0])
                 av_bprintf(bp, "@%s", channel_layout->u.map[i].name);
-
-            if (!av_bprint_is_complete(bp))
-                return AVERROR(ENOMEM);
-
         }
         if (channel_layout->nb_channels) {
             av_bprintf(bp, ")");