Put TIMER_FREQ definition in CPU-specific config, and remove timer-target.h
Note : SH has TIMER_FREQ defined to CPU_FREQ, so any code wanting it must include #config.h before #cpu.h
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21560 a1c6a512-1295-4272-9138-f99709370657