ftrace: check proper config for preempt type

There is no CONFIG_PREEMPT_DESKTOP. Use the proper entry CONFIG_PREEMPT.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/trace/trace.c

@@ -1341,7 +1341,7 @@ print_trace_header(struct seq_file *m, struct trace_iterator *iter)
 		   "server",
 #elif defined(CONFIG_PREEMPT_VOLUNTARY)
 		   "desktop",
-#elif defined(CONFIG_PREEMPT_DESKTOP)
+#elif defined(CONFIG_PREEMPT)
 		   "preempt",
 #else
 		   "unknown",