tracing: Add TRACE_SYSTEM_VAR to intel-sst

New code will require TRACE_SYSTEM to be a valid C variable name,
but some tracepoints have TRACE_SYSTEM with '-' and not '_', so
it can not be used. Instead, add a TRACE_SYSTEM_VAR that can
give the tracing infrastructure a unique name for the trace system.

Link: http://lkml.kernel.org/r/20150402142831.GT6023@sirena.org.ukAcked-by: Mark Brown <broonie@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>

include/trace/events/intel-sst.h

 #undef TRACE_SYSTEM
 #define TRACE_SYSTEM intel-sst
 
+/*
+ * The TRACE_SYSTEM_VAR defaults to TRACE_SYSTEM, but must be a
+ * legitimate C variable. It is not exported to user space.
+ */
+#undef TRACE_SYSTEM_VAR
+#define TRACE_SYSTEM_VAR intel_sst
+
 #if !defined(_TRACE_INTEL_SST_H) || defined(TRACE_HEADER_MULTI_READ)
 #define _TRACE_INTEL_SST_H