net: netfilter: IRC DCC for private clients

Added support for IRC DCC for private clients
by avoiding NAT if the DCC client is a
private client.

Change-Id: I786724e82768317e4f511733bc9247e81d2b60a6
Signed-off-by: Mohammed Javid <mjavid@codeaurora.org>
Acked-by: Sudhanshu Singh <sudhsing@qti.qualcomm.com>