STPK-1429 Add support for custom trigger names

STPK-1429 Add support for custom trigger names

    The Bosch BMC150 magnetometer driver exposes a different
    trigger name than the usual sensor-name-devX. Add support for
    this, so the enable buffer operation succeeds. There seems to
    be remaining issues with channels not being enabled though,
    so this change is not enough to get the magnetometer working
    on the ECS board. Also, the driver does not expose a sampling
    rate control knob.

    Issue: STPK-1429

Change-Id: I2a145a597c0ba4f95beeb86d385d3c774889d9e8
Signed-off-by: Patrick Porlan <patrick.porlan@intel.com>