Update submodule matrix to latest Fri Aug 28 00:40:08 UTC 2020

    - matrix in PX4/Firmware (5d01472): PX4/PX4-Matrix@25c0455
    - matrix current upstream: PX4/PX4-Matrix@ce6b10b
    - Changes: PX4/PX4-Matrix@25c0455...ce6b10b

    ce6b10b 2020-08-27 Julian Oes - Fix clang-tidy warnings
13f092a 2020-08-26 Kamil Ritz - sparse quadratic form
3a5bfb2 2020-08-25 Julian Oes - matrix: inline to prevent multiple definitions (#147)
e101edc 2020-08-24 Julian Oes - Matrix: fix warning if M == N (#146)
cd8ad15 2020-08-24 Morten Fyhn Amundsen - Make wrap() work with integer types (#145)