[tests] update imu_b2_2 test to use hmc58xx driver
[stm32][spi] no functional changes, only readability/comments/dox
[tests] ms2100 magnetometer test prog
[stm32][ms2100] hopefully fix it?
[peripherals] ms2100 mag: don't unselect between request and read
- lock the spi between req and read
- submit requests for next axis from event loop until all 3 axes are read