Set the serial console to ttyS1 in raccoon

Apparently the ttyS0 console doesn't exist but ttyS1 does:

  raccoon% sudo stty -F /dev/ttyS0
  stty: /dev/ttyS0: Input/output error
  raccoon% sudo stty -F /dev/ttyS1
  speed 9600 baud; line = 0;
  -brkint -imaxbel

The dmesg line agrees:

  00:03: ttyS1 at I/O 0x2f8 (irq = 3, base_baud = 115200) is a 16550A

The console configuration is then moved from base to xeon to allow
changing it for the raccoon machine.

Reviewed-by: Aleix Boné <abonerib@bsc.es>

m/common/xeon/console.nix

@@ -5,4 +5,10 @@
     wantedBy = [ "getty.target" ];
     serviceConfig.Restart = "always";
   };
+
+  # Enable serial console
+  boot.kernelParams = [
+    "console=tty1"
+    "console=ttyS0,115200"
+  ];
 }