samr21: 32 hwtimer

The hwtimer did not work correctly on the samr21-xpro, I accidentally read that it has to use a 32 bit timer,
So I changed the timer peripheral to have 1 16-bit timer and 1 32-bit timer, and the hwtimer is now using the 32 bit timer.

Sure the board is only running with 8MHz? Seems like either this value here is wrong or the core clock is not configured correctly...