docker: Add Requires on docker service

docker: Add Requires on docker service

When using docker container engine then the systemd unit scripts only
use a dependency on the docker daemon via the After parameter.
But if docker is restarted on a live system then the ceph systemd units
should wait for the docker daemon to be fully restarted.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1846830
Signed-off-by: Dimitri Savineau <dsavinea@redhat.com>