iio: bmc150: refactor interrupt enabling

This patch combines the any motion and new data interrupts function
into a single, generic, interrupt enable function. On top of this, we
can later refactor triggers to make it easier to add new triggers.

Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>