devfs: Remove references to specific device managers

There were references in the devfs script to mdev, udev and
udev-mount. These all provide the virtuals dev and dev-mount; that is
how we should refer to them.

I believe in the discussion I had with Tony and Robin about this, we
were going to change the "use" line to "need". However, after thinking
that over, I'm not comfortable doing so because someone could be running
a static /dev with no device manager.

Reported-by: <tokiclover@gmail.com>
X-Gentoo-Bug: 438932
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=438932

init.d/devfs.in

@@ -5,8 +5,8 @@
 description="Mount system critical filesystems in /dev."
 
 depend() {
-	use dev-mount udev-mount
-	before udev mdev
+	use dev-mount
+	before dev
 	keyword -prefix -vserver
 }