Rename ambe3600x2250 to ambe3600x2450 to correctly reflect the codec type

This renames ambe3600x2250 to 3600x2450. This variant of AMBE has 49 speech bits and 23 FEC bits for a total bitrate of 3600bps, therefore 2450bps is used for speech and 1150bps is used for FEC.

This will break dsd; a PR to fix dsd will be submitted shortly.