Update submodule ecl to latest Mon Apr 27 12:39:40 UTC 2020

    - ecl in PX4/Firmware (2723251): PX4/PX4-ECL@8a9d961
    - ecl current upstream: PX4/PX4-ECL@8b6d665
    - Changes: PX4/PX4-ECL@8a9d961...8b6d665

    8b6d665 2020-04-26 kamilritz - Avoid subtraction of two uint
70d65ea 2020-04-16 kamilritz - Test:Increase GPS jump need for rejection
c19f40e 2020-04-15 Kamil Ritz - Add reset position test for GPS and VISION
78a6b9f 2020-04-15 Kamil Ritz - SensorSimulator: Fix GPS horizontal position step
050298f 2020-04-08 Kamil Ritz - Improve matrix library usage
5749273 2020-04-08 Kamil Ritz - refactor resetPosition