rfs: call sock_rps_record_flow() in tcp_splice_read()

call sock_rps_record_flow() in tcp_splice_read(), so the applications using
splice(2) or sendfile(2) can utilize RFS.
Signed-off-by: NChangli Gao <xiaosuo@gmail.com>
----
 net/ipv4/tcp.c |    1 +
 1 file changed, 1 insertion(+)
Signed-off-by: NDavid S. Miller <davem@davemloft.net>