update Treo680, generalise it and add Centro support - round 2

Hi,

this is second round of patch set updating Treo680, generalising it and adding support for Palm Centro.

Changes since last time:
 - patch set generated properly (with respect of file renames)
 - fixed name of keyboard backlight LED (now treo680:white:keybbl, centro:white:keybbl)

Thanks for your time and comments.

Best regards,

Tomas Cech