bmi160: add C driver and example. Add SPI support, other improvments.

This adds SPI support to the BMI160, as well as a C driver and a C
example.  In addition, some changes were made to more properly detect
and handle errors.

Functions supplied by the bosch_bmi160 driver source code is also
exported and made available to callers who want more than what the
basic driver support.  Bus access methods (I2C and SPI) are also now
exposed to both C and C++.

Signed-off-by: Jon Trulson <jtrulson@ics.com>

src/bmi160/bosch_bmi160.c

@@ -101,7 +101,8 @@ struct yas_vector fifo_vector_xyz;
  *	(Better case don't change the reference value of the parameter)
  *
 */
-BMI160_RETURN_FUNCTION_TYPE bmi160_init(struct bmi160_t *bmi160)
+/* JET - renamed from bmi160_init to avoid conflict with UPM code */
+BMI160_RETURN_FUNCTION_TYPE bmi160_init_bus(struct bmi160_t *bmi160)
 {
 	/* variable used for return the status of communication result*/
 	BMI160_RETURN_FUNCTION_TYPE com_rslt = E_BMI160_COMM_RES;