package/haveged: change systemd service file to run earlier

package/haveged: change systemd service file to run earlier

Drop default dependencies, haveged needs nothing but local sockets and
/dev/random.

The service file now mostly matches the upstream Fedora file, except a
lot of isolation options have been dropped. The benefit for a
completely controlled system is small, and those option would pull in
dependencies, delaying entropy being filled up.

Signed-off-by: Norbert Lange <nolange79@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>