Replace the previous not-implemented interface with a set of new methods
that can be resonably implemented:
- register_periodic_callback() now receives a functor returning bool
to easily allow "oneshot" timers
- adjust_periodic_callback() allows the caller to change the timer
for a specific handle. This way drivers like MS5611 can adjust the
timer depending on its state machine: the time to sample
temperature is smaller than the time to get a pressure sample
- add unregister_callback(): since we have an opaque pointer, we
can't tell the user to just delete it in order to unregister the
callback
This method is needed when we want to transfer both tx and rx at the
same time, as opposed to common cases for sensors in which they are like
in the I2C interface: half-duplex.
Lucas De Marchi
Gustavo Jose de Sousa