The way this patch has been written is a bit inconsistent with other
parts, but this is the way to go: values should be clear for the user
and not to be interpreted according to the board type. So, for timer
trigger we talk about seconds and nanoseconds, instead of seconds and
coarse.

Another thing to be noted here is that the FMCADC100M has 64bit seconds
while the library supports only 32bit. I leave it like this before to
get something working as soon as possible.
Signed-off-by: Federico Vaga <federico.vaga@cern.ch>