GMIN-2525: Ensure that we select a motion trigger if available

GMIN-2525: Ensure that we select a motion trigger if available

Srinivas is adding alternate "any-motion" triggers to a variety
of iio drivers. Let's use these in priority, and engage the HAL
level event repetition machinery if we select such a trigger.

This is dependent on the trigger name being advertised through
/sys/bus/iio/devices/triggerX.

Issue: GMIN-2525

Change-Id: I5e8c717df9b2716ded175e3522ea505c70eaf8b9
Signed-off-by: Patrick Porlan <patrick.porlan@intel.com>