[NETFILTER]: Fix missing src port initialization in tftp expectation mask

Reported by David Ahern <dahern@avaya.com>, netfilter bugzilla #426.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/netfilter/ip_conntrack_tftp.c

@@ -71,6 +71,7 @@ static int tftp_help(struct sk_buff **pskb,
 
 		exp->tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
 		exp->mask.src.ip = 0xffffffff;
+		exp->mask.src.u.udp.port = 0;
 		exp->mask.dst.ip = 0xffffffff;
 		exp->mask.dst.u.udp.port = 0xffff;
 		exp->mask.dst.protonum = 0xff;