s4-common: make akmd a device-specific binary

* ville uses it in conjunction with the Panasonic IMU, and has a special
  driver for it.
* ville version: ville-3.16.401.8
* evita/jewel use it in conjunction with the MPU3050 IMU.
* fireball uses a standalone AKM8975.
* other versions: evita-5.08.111.2