tracing, net, skb tracepoint: make skb tracepoint use the TRACE_EVENT() macro

TRACE_EVENT is a more generic way to define a tracepoint.
Doing so adds these new capabilities to this tracepoint:

  - zero-copy and per-cpu splice() tracing
  - binary tracing without printf overhead
  - structured logging records exposed under /debug/tracing/events
  - trace events embedded in function tracer output and other plugins
  - user-defined, per tracepoint filter expressions

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: "Steven Rostedt ;" <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <49DD90D2.5020604@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>