Neo players' "select" button works as the "ON" button does on the Archos
players. I thus #define BUTTON_ON to the select one, to make the code all
over automaticly adjust to this fact.
If the select key turns out to be a bad choice, it should be easy to change
here to a more suitable key.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@4157 a1c6a512-1295-4272-9138-f99709370657