Introduce TIMER_FREQ define. git-svn-id: svn://svn.rockbox.org/rockbox/trunk@9067 a1c6a512-1295-4272-9138-f99709370657
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@7576 a1c6a512-1295-4272-9138-f99709370657
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@7242 a1c6a512-1295-4272-9138-f99709370657