tracing, genirq: add irq enter and exit trace events

tracing, genirq: add irq enter and exit trace events

Impact: add new tracepoints

Add them to the generic IRQ code, that way every architecture
gets these new tracepoints, not just x86.

Using Steve's new 'TRACE_FORMAT', I can get function graph
trace as follows using the original two IRQ tracepoints:

 3)               |    handle_IRQ_event() {
 3)               |    /* (irq_handler_entry) irq=28 handler=eth0 */
 3)               |    e1000_intr_msi() {
 3)   2.460 us    |      __napi_schedule();
 3)   9.416 us    |    }
 3)               |    /* (irq_handler_exit) irq=28 handler=eth0 return=handled */
 3) + 22.935 us   |  }

Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>