[NET/IPv4]: Make udp_push_pending_frames static

udp_push_pending_frames is only referenced within
net/ipv4/udp.c and hence can remain static.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/udp.c

@@ -448,7 +448,7 @@ static void udp4_hwcsum_outgoing(struct sock *sk, struct sk_buff *skb,
 /*
  * Push out all pending data as one UDP datagram. Socket is locked.
  */
-int udp_push_pending_frames(struct sock *sk, struct udp_sock *up)
+static int udp_push_pending_frames(struct sock *sk, struct udp_sock *up)
 {
 	struct inet_sock *inet = inet_sk(sk);
 	struct flowi *fl = &inet->cork.fl;