LSM9DS1: fix mag out register and acc fullscale.

Signed-off-by: Giuseppe Barba <giuseppe.barba@gmail.com>
Default exception handler debug.

Add store of registers status for debugging when the system goes
to execute the default exception handler. In this status the
pc register could be used to retrieve the function that was
called before the system goes in exeception state.

Signed-off-by: Giuseppe Barba <giuseppe.barba@gmail.com>