uboot: (firmwareOdroidC2/C4) don't invoke patch tool, use patches = [] instead

https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L948
this can do it nicely.

Signed-off-by: Anton Arapov <anton@deadbeef.mx>

nixos/doc/manual/administration/user-sessions.chapter.md

@@ -0,0 +1,43 @@
+# User Sessions {#sec-user-sessions}
+
+Systemd keeps track of all users who are logged into the system (e.g. on
+a virtual console or remotely via SSH). The command `loginctl` allows
+querying and manipulating user sessions. For instance, to list all user
+sessions:
+
+```ShellSession
+$ loginctl
+   SESSION        UID USER             SEAT
+        c1        500 eelco            seat0
+        c3          0 root             seat0
+        c4        500 alice
+```
+
+This shows that two users are logged in locally, while another is logged
+in remotely. ("Seats" are essentially the combinations of displays and
+input devices attached to the system; usually, there is only one seat.)
+To get information about a session:
+
+```ShellSession
+$ loginctl session-status c3
+c3 - root (0)
+           Since: Tue, 2013-01-08 01:17:56 CET; 4min 42s ago
+          Leader: 2536 (login)
+            Seat: seat0; vc3
+             TTY: /dev/tty3
+         Service: login; type tty; class user
+           State: online
+          CGroup: name=systemd:/user/root/c3
+                  ├─ 2536 /nix/store/10mn4xip9n7y9bxqwnsx7xwx2v2g34xn-shadow-4.1.5.1/bin/login --
+                  ├─10339 -bash
+                  └─10355 w3m nixos.org
+```
+
+This shows that the user is logged in on virtual console 3. It also
+lists the processes belonging to this session. Since systemd keeps track
+of this, you can terminate a session in a way that ensures that all the
+session's processes are gone:
+
+```ShellSession
+# loginctl terminate-session c3
+```