Fix udev rule required by gpm

Backport: 14.04

nixos/modules/services/hardware/udev.nix

@@ -22,7 +22,7 @@ let
     KERNEL=="kqemu",                MODE="0666"
 
     # Needed for gpm.
-    KERNEL=="input/mice", TAG+="systemd"
+    SUBSYSTEM=="input", KERNEL=="mice", TAG+="systemd"
   '';
 
   # Perform substitutions in all udev rules files.

nixos/modules/services/ttys/gpm.nix

@@ -45,6 +45,7 @@ in
 
         wantedBy = [ "multi-user.target" ];
         requires = [ "dev-input-mice.device" ];
+        after = [ "dev-input-mice.device" ];
 
         serviceConfig.ExecStart = "@${pkgs.gpm}/sbin/gpm gpm -m /dev/input/mice -t ${cfg.protocol}";
         serviceConfig.Type = "forking";