Update submodule ecl to latest Fri Dec 18 00:39:53 UTC 2020

- ecl in PX4/Firmware (dc358857c877ae01b922d84a6c6fffe6d8c46810): https://github/commit/1541e4b414fe63ec9d6c3077375db7e20c20ef4a
    - ecl current upstream: https://github/commit/a8e0e82858318042500f96f5ee882c638f201426
    - Changes: https://github/compare/1541e4b414fe63ec9d6c3077375db7e20c20ef4a...a8e0e82858318042500f96f5ee882c638f201426

    a8e0e82 2020-12-08 Daniel Agar - EKF: update mag LPF immediately
398fe15 2020-11-02 Daniel Agar - EKF: allow initialising without mag depending on configuration
1237087 2020-12-16 Daniel Agar - AlphaFilter add constructor that takes alpha and use in EKF
37e84b7 2020-12-16 Daniel Agar - README: fix zenodo badge (rename ecl -> PX4-ECL)
5ccb8b4 2020-12-15 Mathieu Bresciani - fakePosFusion: reset _last_known_posNE to current state when starting (#943)
9d22f14 2020-12-10 bresch - gps_alt: constrain var using 1.5 as a typical ratio of vacc/hacc
b0cf45e 2020-12-10 bresch - gps_alt: rename getGpsAltVar -> getGpsHeightVariance
62f2e26 2020-12-10 bresch - gps_alt: reset GPS alt variance usign helper function
f7bddda 2020-12-10 bresch - gps_alt: do not scale up reported gps vertical accuracy
02369cd 2020-12-10 bresch - gps_alt: extract measurement variance computation and saturation

src/lib/ecl

@@ -1 +1 @@
-Subproject commit 1541e4b414fe63ec9d6c3077375db7e20c20ef4a
+Subproject commit a8e0e82858318042500f96f5ee882c638f201426