wibble
ivory-px4-hw: fix statemachine usage for mpu6000 driver

result: this makes the mpu6000 test give output that looks, at first glance,
kinda sorta sane. not sure if the gyro data is good but the accel looks ok.
ivory-px4-tests: add clean targets to makefile
fixup
ivory-px4-tests: fix ms5611 and hmc5883 drivers so they start after init