gst1-plugins-bad: remove mpg123 plugin option

The plugin was moved from -bad to -ugly so remove the option.
Support in -ugly was added via 30cde9a3.
Add legacy entry to notify users of this, however we can't automatically
select the ugly variant since ugly might be disabled.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
3 files changed