display.h: show max string length

provide max else build fails

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
diff --git a/display.h b/display.h
index 035b2e9..6362a48 100644
--- a/display.h
+++ b/display.h
@@ -32,3 +32,5 @@
 extern int display_init(int wdefault);
 extern int display_register(int win, struct display_ops *ops);
 extern int display_column_name(const char *line);
+
+#define NAME_MAX 255