tools/power turbostat: fix output buffering issue

In periodic mode, turbostat writes to stdout,
but users were un-able to re-direct stdout, eg.

turbostat > outputfile

would result in an empty outputfile.
Signed-off-by: Len Brown <len.brown@intel.com>

tools/power/x86/turbostat/turbostat.c

@@ -423,6 +423,7 @@ int format_counters(struct thread_data *t, struct core_data *c,
 void flush_stdout()
 {
 	fputs(output_buffer, stdout);
+	fflush(stdout);
 	outp = output_buffer;
 }
 void flush_stderr()