net: tcp: use tcp_drop_reason() for tcp_data_queue_ofo()

Replace tcp_drop() used in tcp_data_queue_ofo with tcp_drop_reason().
Following drop reasons are introduced:

SKB_DROP_REASON_TCP_OFOMERGE

Reviewed-by: Mengen Sun <mengensun@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>