Revert "HAL_PX4: read from FRAM in 128 byte chunks"

This reverts commit a92366c4552851719cbdd0e5a92789f99f8bda6d.

This commit may be associated with FRAM corruption on Pixhawk. Revert
until we understand why
HAL_PX4: read from FRAM in 128 byte chunks (2nd try)

this time without the amazingly silly bug
AP_NavEKF: Add ability to inhibit in-flight mag cal and clean up moding

This will enable in-flight magnetometer calibration to be inhibited unconditionally,
This is required for long balloon carriage flights where ground speed can be high
enough to put it into in-air state, but with very poor observability of magnetic field
states causing bad state estimates and heading offsets to develop over time.

The mode control for wind and magnetic field state inhibit has also been explicitly
defined and cleaned up
AP_NavEKF: Use baro data during launch transients whilst in static mode

Baro data can be used as it will still be valid during the launch and
is not a synthesised measurement.