main/udev-init-scripts: make the udev init script provide dev

The OpenRC scripts for mdev and mdevd already provide the "dev" virtual service. Align the udev script on them, so that no two device managers are started at the same time.

To do this, we replace the modloop patch by a modloop-and-dev patch instead of having a separate patch because it's a very simple change and at the same place in the file. It's easier to do it in the same patch than to have 2 separate patches touching the same file at the same place (enforcing patch order, etc.)