iwlwifi: add new firmware for 2000 devices

http://intellinuxwireless.org/iwlwifi/downloads/iwlwifi-2000-ucode-18.168.6.1.tgz

Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

WHENCE

@@ -745,6 +745,9 @@ Info: v39.31.5.1
 File: iwlwifi-105-6.ucode
 Info: v18.168.6.1
 
+File: iwlwifi-2000-6.ucode
+Info: v18.168.6.1
+
 Licence: Redistributable. See LICENCE.iwlwifi_firmware for details
 
 Also available from http://intellinuxwireless.org/?n=Downloads