package/network-manager: adapt to systemctl preset-all

package/network-manager: adapt to systemctl preset-all

NM has three services
* NetworkManger.service : the main daemon
* NetworkManger-dispatcher.service : a daemon handling network callbacks
* NetworkManager-wait-online.service : sync of other services with network-online

Only the first two were activated. We now also enable
wait-online. Not enabling it was probably a bug.

Note that buildroot adds an alias dbus-org.freedesktop.NetworkManager
Adding an alias that is not known upstream is not clean,
but I left it for backward compatibility

Signed-off-by: Jérémy Rosen <jeremy.rosen@smile.fr>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>