AK8963 scalings should use individual components

[simonjwright]

In components/src/motion/ak8963/ak8963.adb, procedure Get_Heading, it says

     if Status = Ok then
        Mx := Mx * ((Float (Buffer (1)) - 128.0) / 256.0 + 1.0);
        My := My * ((Float (Buffer (1)) - 128.0) / 256.0 + 1.0);
        Mz := Mz * ((Float (Buffer (1)) - 128.0) / 256.0 + 1.0);
     end if;

The Y component should use Buffer (2), the Z component should use Buffer (3).

[lambourg]

Thanks Simon, this is now fixed.