drivers: sensor: lsm6dsl: correct initialization order

The function that initializes interrupts configures the sensor
register to enable interrupts.  It is called before the function that
resets the sensor.  Swap the order.

Also correct the mask argument to the configuration command, and use
the BIT() macro to construct the set argument.

Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>