lockdep: Use KSYM_NAME_LEN'ed buffer for __get_key_name()

Not a big deal, but since other __get_key_name() callers
use it lets be consistent.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20121020190519.GH25467@moonSigned-off-by: Ingo Molnar <mingo@kernel.org>

kernel/lockdep_proc.c

@@ -39,7 +39,7 @@ static void l_stop(struct seq_file *m, void *v)
 
 static void print_name(struct seq_file *m, struct lock_class *class)
 {
-	char str[128];
+	char str[KSYM_NAME_LEN];
 	const char *name = class->name;
 
 	if (!name) {