4.0 adds systemd support but installs the unit files in the wrong location.
Fix this in do_install and inherit systemd to package them correctly.
Also fix ownership of files manually copied in to root:root to avoid QA warnings.
(From OE-Core rev: 74833a612cc383679bb5516e98c7508da47b0767)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>