of: add 'of_' prefix to machine_is_compatible()

machine is compatible is an OF-specific call.  It should have
the of_ prefix to protect the global namespace.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Michal Simek <monstr@monstr.eu>
diff --git a/drivers/char/hvc_beat.c b/drivers/char/hvc_beat.c
index 0afc8b8..9b397c5 100644
--- a/drivers/char/hvc_beat.c
+++ b/drivers/char/hvc_beat.c
@@ -99,7 +99,7 @@
 
 static int __init hvc_beat_console_init(void)
 {
-	if (hvc_beat_useit && machine_is_compatible("Beat")) {
+	if (hvc_beat_useit && of_machine_is_compatible("Beat")) {
 		hvc_instantiate(0, 0, &hvc_beat_get_put_ops);
 	}
 	return 0;