update Treo680, generalise it and add Centro support

[Tomáš Čech]

Hi,

this set of patches update Treo680 code a bit and generalise it. It also shows the way I'd like to add other Palm smartphones (Treo 755p and hopefully others). If this is not acceptable way of doing that, tell me, please.

Thanks for your time,

Best regards,

Tomas Cech