Update submodule ecl to latest Mon Aug 10 00:39:38 UTC 2020

    - ecl in PX4/Firmware (eeaec37): PX4/PX4-ECL@7eb2b08
    - ecl current upstream: PX4/PX4-ECL@9d7d502
    - Changes: PX4/PX4-ECL@7eb2b08...9d7d502

    9d7d502 2020-08-09 kamilritz - std::sin -> sin
4ab364f 2020-08-09 kamilritz - Make conversion from float to double explicite
9ea3468 2020-07-07 Julian Kent - Negative distances go in the opposite direction
b7e49f2 2020-08-09 kamilritz - Update change indication
4970088 2020-08-09 kamilritz - Update matrix version
d7568d5 2020-07-28 kamilritz - extend firmware build checks
310b989 2020-08-06 kamilritz - refactor start of gps into separate function