Enhancement: Update reva to v1.6.1-0.20210414111318-a4b5148cbfb2

* enforce quota (https://github.com/cs3org/reva/pull/1557)
* Make additional info attribute configureable (https://github.com/cs3org/reva/pull/1588)
* check ENOTDIR for readlink (https://github.com/cs3org/reva/pull/1597)
* Add wrappers for EOS and EOS Home storage drivers (https://github.com/cs3org/reva/pull/1624)
* eos: fixes for enabling file sharing (https://github.com/cs3org/reva/pull/1619)
* implement checksums in the owncloud storage driver (https://github.com/cs3org/reva/pull/1629)

https://github.com/owncloud/ocis/pull/1872

