Fix: net: expose sk wmem in sock_exceed_buf_limit tracepoint (4.19)

Fix: net: expose sk wmem in sock_exceed_buf_limit tracepoint (4.19)

See upstream commit:

  commit d6f19938eb031ee2158272757db33258153ae59c
  Author: Yafang Shao <laoar.shao@gmail.com>
  Date:   Sun Jul 1 23:31:30 2018 +0800

    net: expose sk wmem in sock_exceed_buf_limit tracepoint

    Currently trace_sock_exceed_buf_limit() only show rmem info,
    but wmem limit may also be hit.
    So expose wmem info in this tracepoint as well.

    Regarding memcg, I think it is better to introduce a new tracepoint(if
    that is needed), i.e. trace_memcg_limit_hit other than show memcg info in
    trace_sock_exceed_buf_limit.

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>