Update LibAudio to optionally use high RAM

[haviital]

The change looks good. Few comments:

• To clean up, I would be good to either to remove now obsolete HIGH_RAM_MUSIC define handling, or make it so that if that is defined , it will set the AUDIO_BUFFER_ADDRESS=0x20000000 as default.
• Also the old audio buffer declarations ("buffers") could be now removed from headers, as it is not actually defined or used any more. (it is still used for Python bindings in Pok_Sound_Reset() but that part can be removed as it has no effect any more, and will not compile anyway ;-) )

[filmote]

These are good ideas .. I will attempt a second PR.