irq/tracing: Export enums in tracepoints to user space

The enums used by the softirq mapping is what is shown in the output
of the __print_symbolic() and not their values, that are needed
to map them to their strings. Export them to userspace with the
TRACE_DEFINE_ENUM() macro so that user space tools can map the enums
with their values.

Link: http://lkml.kernel.org/r/20150403013802.220157513@goodmis.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>