BMI055_AK8975 missing implementation

[JamesWhitlock]

The committed version of src/F_BMI055_AK8975.hpp is an exact duplication of src\F_BMI055_QMC5883L.hpp. The code for BMI055_AK8975 is therefore missing.

[LiquidCGS]

Whoops, I'll take a look at that shortly