units: Rename systemd-udev.service to systemd-udevd.service

This naming convention is more inline with other systemd daemon
unit names (systemd-logind.service, systemd-localed.service etc)

The companion .socket units have also been renamed, however the
-trigger and -settle units keep their current name as these are
not directly related to daemon process itself.

units/systemd-udevd-kernel.socket

@@ -0,0 +1,18 @@
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=udev Kernel Socket
+Documentation=man:systemd-udevd.service(8) man:udev(7)
+DefaultDependencies=no
+ConditionCapability=CAP_MKNOD
+
+[Socket]
+Service=systemd-udevd.service
+ReceiveBuffer=134217728
+ListenNetlink=kobject-uevent 1
+PassCredentials=yes