tracing/kprobes: Make print_*probe_event static

According to sparse warning, print_*probe_event static because
those functions are not directly called from outside.

Link: http://lkml.kernel.org/r/20130513115839.6545.83067.stgit@mhiramat-M0-7522

Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tom Zanussi <tom.zanussi@intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace_kprobe.c

@@ -962,7 +962,7 @@ kretprobe_trace_func(struct trace_probe *tp, struct kretprobe_instance *ri,
 }
 
 /* Event entry printers */
-enum print_line_t
+static enum print_line_t
 print_kprobe_event(struct trace_iterator *iter, int flags,
 		   struct trace_event *event)
 {
@@ -998,7 +998,7 @@ partial:
 	return TRACE_TYPE_PARTIAL_LINE;
 }
 
-enum print_line_t
+static enum print_line_t
 print_kretprobe_event(struct trace_iterator *iter, int flags,
 		      struct trace_event *event)
 {